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LABORATORY  GUIDE  FOR  HISTOLOGY 


H ARDESTY 


A   LABORATORY 
GUIDE   FOR   HISTOLOGY 


Laboratory  Outlines  for  the  Study  of  Histology 
and  Microscopic  Anatomy 


BY 

IRVING  HARDESTY,  A.B.,  Ph.D. 

Associate  Professor  of  Anatomy  in  the  University  of  California. 


WITH  A  CHAPTER  ON  LABORATORY  DRAWING  BY 

ADELEBERT  WATTS  LEE,  M.  D. 

Assistant   in    Anatomy   in    the    University    of   California. 


WITH  30  ILLUSTRATIONS  2  OF  WHICH  ARE  IN  COLORS 


PHILADELPHIA 

P.   BLAKISTON'S  SON   &   CO. 

1012   WALNUT   STREET 
1908 


Copyright,   igo8,  by  P.  Blakiston's  Son  &  Co. 


I'riuli'd  by 

The  Maple.  Press 

)-ork.  Pa. 


PREFACE 


The  purpose  of  this  little  book  is  economy  of  time  and  labor  for  both  the 
Instructor  and  Student.  It  is  a  common  experience  in  our  Anatomical  Labora- 
tories that  the  student  taking  courses  in  Histology  and  Microscopic  Organology 
spends  a  large  part  of  his  time  in  doing  things  which  are  not  essential  to  the 
accomplishment  of  the  actual  purpose  of  the  courses.  He  wastes  time  in 
vague  application  of  histological  technic  which  is  involved  in  neither  the 
title  nor  the  real  purport  of  the  work.  He  proceeds  to  study  a  subject  without 
a  definite  concept  of  what  is  best  to  be  done  and  how  best  to  go  about  it,  and 
without  forethought  of  economic  distribution  and  use  of  his  time.  He  will 
begin  a  drawing  from  a  preparation  without  having  first  decided  what  special 
features  the  drawing  should  most  advisably  illustrate,  without  having  thought 
out  the  amount  of  magnification  and  the  style  of  drawing  most  suited  to  the 
purpose.  The  too  frequent  consequence  is  that  the  time  allotted  to  a  course 
is  so  poorly  utilized  that  the  student  actually  covers  a  far  smaller  portion  of  the 
ground  purported  to  be  the  object  of  the  course  than  he  may  be  led  to  cover 
if  guided  in  a  more  definite  manner  as  to  what  to  do  and  how  to  proceed. 

This  Laboratory  Guide,  therefore,  is  offered  to  the  student  and  instructor 
with  the  hope  that  it  will  be  an  aid  toward  the  accomplishment  of  a  greater 
amount  of  that  work  which  may  be  correctly  designated  The  Study  of  Histology 
and  Microscopic  Anatomy,  and  an  aid,  further,  toward  an  improvement  in  the 
quality  of  that  v^ork.  On  the  other  hand,  it  is  not  intended  that  it  shall,  in 
any  way,  lessen  the  tendency  to  nor  decrease  the  amount  of  independent  work 
on  the  part  of  the  student  as  regards  all  the  essential  features  of  his  studies. 
Rather,  the  suggestion  and  stimulation  of  independent  thought  has  been  kept 
in  mind  throughout  the  construction  of  the  guide. 

The  Outlines  as  here  given  embody  what  the  author  has  used  with  his 
classes  during  the  past  six  years.  Corrected  and  revised  from  year  to  year, 
they  have  heretofore  been  issued  to  the  student  in  mimeographed  form  and, 
in  their  revision,  restriction  has  been  more  and  more  made  to  those  studies 
deemed  most  essential  and  to  the  amount  of  work  which  experience  has  shown 
that  the  average  class  in  Histology  may  be  induced  to  cover  in  the  allotted  time. 

As  offered  by  the  author,  the  entire  work  has  required  the  equivalent  of 
three  three-hour  periods  per  week  throughout  one  school  year.  The  time 
has  been  so  arranged  as  to  offer  the  work  in  three  courses:  (i)  Histology 
proper;  (2)  Microscopic  Anatomy  of  the  Organs,  exclusive  of  the  Central 
Nervous  System   and    Sense-Organs;    (3)  The  Central  Nervous  System   and 

V 


VI  PREFACE. 

Organs  of  Special  Sense.  In  medical  schools,  the  third  course  is  more  ad- 
visedly given  to  students  in  the  second  year  when  they  are  more  mature  from 
experiences  in  other  courses  and  capable  of  more  rapid  and  intelligent  accom- 
plishment. Unfortunately,  some  of  the  schools  in  which  it  is  hoped  this 
Laboratory  Guide  will  be  used  do  not  devote  to  the  work  as  many  hours  as 
are  necessary  to  the  amount  of  work  outlined  here.  In  such  cases,  if  the  time 
cannot  be  increased,  it  will  be  necessary,  of  course,  that  the  instructor  read 
ahead  of  his  class  and  direct  that  such  paragraphs  as  he  deems  less  essential 
be  omitted.  It  should  be  remembered,  however,  that  certain  of  the  time 
called  for  here  is  devoted  to  studies  of  the  detailed  gross  anatomy  of  the  organs, 
not  only  for  the  value  of  such  studies  per  se,  but  in  order  to  bridge  that  too 
common  gap  between  Gross  and  Microscopic  Anatomy,  and  that,  therefore, 
the  whole  time  is  not  demanded  for  purely  microscopic  structures.  Especially 
is  this  true  of  the  portion  dealing  with  the  central  nervous  system,  which  por- 
tion is  intended  to  comprise  the  only  study  made  by  the  student  of  the  gross 
anatomy  of  this  system. 

It  is  a  common  experience  that  the  student's  laboratory  drawings  in  His- 
tology are  a  matter  of  troublesome  as  well  important  necessity.  In  order  that 
the  student,  so  often  wholly  unskilled  in  drawing,  may  obtain  some  idea  of 
the  simpler  principles  involved  in  graphic  art,  Dr.  A.  W.  Lee  has  kindly  pre- 
pared a  chapter  on  laboratory  drawing.  This  Laboratory  Guide  is  especially 
fortunate  in  its  incorporation  of  this  chapter,  for  it  is  a  subject  in  which  syste- 
matic instruction  is  very  seldom  given,  and  not  only  is  Dr.  Lee  himself  an  artist 
of  marked  ability,  but  he  has  given  considerable  study  to  this  variety  of  drawing. 
The  chapter  involves  directions  as  to  equipment  and  for  such  procedures  and 
processes  as  are  considered  most  essential  for  the  student  in  the  laboratory. 
The  original  drawings  illustrating  the  chapter  are  purposely  reproduced 
here  without  reduction  that  they  may  be  more  instructive  as  to  the  direct 
effects  the  student  may  accomplish  in  his  laboratory  drawings. 

Berkeley,  California,  August,  1908.  I.  H. 


CONTENTS. 


Laboratory  Drawing i 

Outlines  for  Laboratory  Work 30 

Introductory  Exercises 43 

The  Tissues 47 

Epithelium 47 

The  Supporting  and   Connective  Tissues 51 

Blood  and  Lymph 59 

The  Muscular  Tissues 67 

The  Nervous  Tissues 71 

The  Circulatory  System  . 76 

The  Digestive  Apparatus 89 

The  Respiratory  Apparatus 103 

The  Urino-Genital  System 106 

The  Central  Nervous  System 119 

The  Organs  of  Special  Sense 160 

The  Methods  of  Preparation  Employed 1 79 

Index 191 


vu 


LABORATORY  GUIDE  FOR  HISTOLOGY. 


SECTION  I. 

LABORATORY  DRAWING. 

Drawing  of  microscopical  preparations  has  become  such  an  integral  part 
of  the  routine  class-work  in  histology  and  microscopic  organology,  that  it  is 
thought  advisable  to  include  in  this  Laboratory  Guide  a  brief  description  of 
certain  of  the  materials  and  the  methods  used  to  express  upon  paper  the  struc- 
tures revealed  by  the  microscope.  The  prices  given  under  the  description  of 
the  respective  articles  may  vary  somewhat  with  the  locality,  but  on  the  whole 
may  be  taken  as  quite  approximate. 

Technical  art  terms,  even  those  that  have  become  part  of  nearly  ever^'one's 
vocabulary,  have  likewise  been  avoided  in  order  that  the  clearness  of  description 
might  not  be  obscured  in  any  manner.  The  individual  who  "can't  draw" 
has  constantly  been  kept  in  mind;  in  fact,  this  chapter  was  undertaken  solely 
for  his  benefit.  It  is  quite  true  that  as  yet  no  formula  has  been  given  which 
can  supply  what  Nature  has  not  endowed,  or,  to  put  this  idea  an  other  words, 
no  one  can  learn  to  draw  simply  by  reading  a  list  of  instructions.  But,  it  is, 
nevertheless,  a  fact  that  the  ungifted  will  find  his  task  easier  if  he  has  been  told 
how  to  go  about  it.     The  following  pages  will  attempt  to  do  that  much. 

DRAWING  MATERIALS. 

These  may  be  described  under  two  heads:  those  used  in  making  black  and 
white  drawings  and  those  employed  when  colors  are  necessar}' . 

The  articles  common  to  both  black  and  white  drawing  and  drawing  in  color 
will  be  considered  first.  These  are,  drawing-board,  hand-rest,  thumb-tacks, 
papers,  pencils,  erasers,  pens,  pen  holders,  black  pigments  and  mixing-dish. 

Drawing-board. — The  use  of  the  mere  surface  of  the  work-table  for  draw- 
ing, frequently  practiced  in  laboratories,  is  not  conducive  to  the  best  results. 
Not  only  is  the  wood  of  the  table  often  not  adapted  to  the  necessary  use  of 
thumb-tacks  for  holding  the  drawing-paper  in  place,  but  the  continued  use  of 
the  thumb-tacks  results  in  a  needless  disfiguring  of  the  table.  Furthermore, 
the  table  top  does  not  allow  the  conveniences  of  work  upon  an  inclined  plane, 
when  desired,  nor  manipulation  of  the  position  of  the  fixed  drawing-paper 
while  at  work,  and,  being  used  in  common  for  the  reagents  and  other  materials 
employed  in  the  work,  soiling  of  the  paper  often  results.     The  use  of  a  small 


2  LABORATORY    GUIDE    FOR    HISTOLOGY. 

drawing-board  is  advised.  There  is  no  need  to  buy  this,  as  a  very  serviceable 
one  can  be  made  from  any  piece  of  unwarped,  smooth,  soft  wood.  It  should 
be  cut  about  8  inches  wide  by  12  inches  long.  Boards  of  greater  dimensions 
than  these  should  be  avoided,  because  of  the  unused  space  they  occupy  and  their 
clumsiness  iii  handling  and  use  with  the  microscope.  Flush  with  one  end  of 
the  board,  and  on  its  under  side,  a  thin  strip  of  wood  may  be  nailed;  that  is, 
if  the  operator  cares  to  work  constantly  upon  an  inclined  plane.  If  a  flat 
surface  is  preferred,  the  strip,  of  course,  will  be  omitted,  or,  for  occasional  use, 
need  not  be  attached  to  the  board.  The  softness  of  the  wood  permits  an  easy 
insertion  and  extraction  of  thumb-tacks,  and  its  consequent  lightness  facilitates 


Fig.  I. — Illustrating  the  use  of  the  drawing-board,  b,  and  hand-rest,  a,  and  the  proper 
position  for  a  right-handed  person  when  drawing  microscopical  preparations.  The  raised 
end  of  the  hand-rest  a,  is  placed  upon  the  drawing-board  b,  and  its  other  end  allowed  to 
rest  on  the  table. 


manipulation  during  the  process  of  drawing,  for,  it  must  be  borne  in  mind, 
that  a  slight  rotation  of  the  paper  this  way  or  that  often  makes  it  possible  to 
j^ut  in  certain  lines  with  a  sureness  and  truthfulness  which  could  not  be  accom- 
plished if  the  drawing  were  immovably  fixed  to  the  work-table. 

Hand-rest. — This  can  easily  be  dispensed  with.  If  it  is  desired,  it  should 
also  be  made  of  light,  smooth  wood.  The  hand-rest  is  such  a  simple  con- 
trivance that  anyone  can  construct  it.  It  merely  consists  of  a  piece  of  thin, 
rigid  wood  some  12  inches  long  by  4  inches  wide,  and  a  thin  strip,  say  |-inch 
square,  nailed  flush  with  one  end  on  its  under  side.  The  object  is,  as  the 
name  imf)lies,  to  furnish  a  support  for  the  hand,  it  often  Ijeing  noticed  that  the 
fine  details  are  better  executed  when  the  hand  is  raised  and  steadied  some 
distance  above  the  paper  than  when  down,  close  upon  it.     Again,  the  hand- 


DRAWING    PAPERS. 


Q 


rest  aids  to  keep  the  drawing  clean,  since  contact  of  the  naturally  moist  skin 
with  the  clear  white  surface  frequently  leaves  a  stain,  especially  if  the  drawing 
is  being  done  upon  some  rough,  absorbent  material,  such  as  Ross  board.  Also, 
the  use  of  a  hand-rest  often  obviates  a  cramping  of  the  fingers  in  long-continued 
drawing.  The  manner  of  using  both  the  drawing-board  and  hand-rest  is 
shown  in  Fig.  i. 

Thumb-tacks. — Fig.  2  gives  three  styles  of  thumb-tacks,  D,  E,  and  F. 
The  first  one  is  by  far  the  best.  It  has  a  solid  cap  over  the  head,  and  can  be 
obtained  in  the  size  pictured,  either  brass  or 
nickel.  E  illustrates  a  variety  in  which  the 
whole  tack  is  made  of  one  piece,  the  point  being 
punched  out  of  the  head  and  turned  down.  The 
one  objection  to  it  is  that  after  some  use  the  point 
either  bends  or  cracks  off  at  its  junction  with  the 
head.  F  shows  a  very  unsatisfactory  style,  which 
should  never  be  selected  if  the  other  varieties  can 
be  obtained.  The  fixed  end  of  the  point  passes 
through  and  presents  in  the  surface  of  the  head. 
Often  but  limited  use  suffices  to  loosen  the  point, 
and  on  some  occasion,  when  being  pushed  home 
into  the  drawing-board,  will  spring  clear  of  the 
head,  and  a  painful  prick  of  the  finger  may  result. 
The  price  of  E  and  F  is  about  the  same  as  that 
oiD. 

Drawing-papers. — Under  this  head  the  so- 
called  drawing-boards  are  also  included.  The 
vast  variety  of  these  papers  excludes  in  these 
pages  anything  like  a  complete  list  of  them. 
Some  attention  will  be  paid  to  certain  of  those 
in  more  common  use. 

U'JiaiDicui's  water-color  paper  is  made  in  a 
number  of  different  surfaces,  but  the  one  termed 
"hot-pressed"  is  the  only  kind  serviceable  for 
ordinary  microscopical  illustration.  It  is  a  paper 
of  beautiful  whiteness  and  just  rough  enough  to  take  easily  the  graphite  of  the 
pencil.  It,  as  well,  is  equally  adapted  to  the  use  of  fluid  pigments.  A  heavy 
hand,  however,  finds  this  paper  not  as  satisfactory  as  the  boards,  since  its 
softness  often  leads  to  a  sticking  of  the  pen  with  consequent  blotting.  This 
paper  can  be  obtained  in  different  sizes  and  thicknesses,  but  2 -ply  Imperial 
will  be  found  quite  convenient  for  all  illustration,  as  this  term  is  here  used 
Hot-pressed,  2 -ply  imperial  is  furnished  at  the  rate  of  two  sheets  for  25  cents. 

If  only  one  kind  of  drawing-paper  were  to  be  recommended,  perhaps  none 
would  be  so  generally  satisfactory  as  that  known  as  Reynolds'  hris/ol  board 
It  is  of  pure  and  permanent  whiteness  and  of  extremelv  hard  surface  and  bodv. 


Fig.  2. — Showing  styles  of 
thumb-tacks,  drawing  pens  and 
a  style  of  one  of  the  cheaper 
and  commonly  used  "  blenders  " 
for  pencil  drawing. 


4  LABORATORY   GUIDE    FOR   HISTOLOGY. 

This  paper,  therefore,  suffers  less  from  "knife-erasures"  than  a  softer  materia 
would  and,  because  of  this  fact,  is  especially  to  be  advised  for  student  work. 
For  pen-and-ink  drawings,  and  even  for  those  done  in  masses  of  fluid  pigment, 
there  is  nothing  better  to  be  had.  But  in  pencil  drawings  its  somewhat 
smooth  surface  makes  it  not  as  satisfactory  for  the  unskilled  hand  as  some  of 
the  rougher  papers,  since  the  graphite  of  the  pencil  is  not  so  easily  taken  as  by 
the  latter.  This  one  unpleasant  feature,  however,  should  not  discourage  a 
trial  of  such  an  otherwise  excellent  paper  even  for  pencil-work.  It  is  sold  in 
different  sizes  and  thicknesses,  but  sheets  12^  inches  by  15  inches  and  of  moderate 
weight  can  be  had  under  the  name  of  "  Cap  2-ply"  for  90  cents  per  dozen. 

Examiner  hoard  is  much  used  because  of  its  very  appropriate  surface  for 
pencil  drawing.  Also  pen  and  ink  give  with  it  equally  good  results.  It  is 
not  pure  white,  however,  leaning  more  to  a  pinkish-cream  color.  It  is  unsatis- 
factory when  "knife-erasures"  have  to  be  made,  as  its  surface  and  body  are 
somewhat  soft.  In  the  Imperial  size  it  is  sold  at  the  rate  of  two  sheets  for  25 
cents. 


8        zr         /         iVz       z 

Fig.  3. — -The  result  of  drawing  a  pencil-point  without  raising  it  from  the  surface, 
over  five  varieties  of  Ross  Board.  The  number  given  under  each  corresponds  to 
the  list-number  by  which  the  style  is  designated. 


The  Strathmore  papers  are  also  of  great  service.  The  bristol  board  of 
this  make  is  sold  in  sheets  measuring  23  x  29  inches  at  the  rate  of  two  for  25 
cents. 

Whatman's  water-color  paper,  Reynolds',  Examiner  and  Strathmore 
bristol  boards  consist  throughout  of  but  one  material,  paper-pulp,  and,  there- 
fore, their  working-surface  is  paper,  whether  smooth  or  rough.  But  there  is 
another  board  on  the  market,  which  consists  of  a  chalk  surface  on  a  paper 
body.  This  is  known  as  stipple  board  and  is  manufactured  by  the  Chas.  J. 
Ross  Company.  The  surface  of  this  paper  is  made  in  a  generous  assortment 
of  patterns  suited  to  different  degrees  of  stipple  effects  and  adapted  to  different 
purposes  in  reproduction,  but  for  drawing  in  microscopic  anatomy  not  more 
than  six  of  them  are  applicable. 

The  patterns  are  listed  and  referred  to  by  numbers,  so  when  ordering  one 
asks  for  Ross  stipple  board  No.  i,  i^,  2,  27,  etc.  For  most  work  Nos.  i 
and  27  will  be  used,  but  there  are  instances  where  i\,  2  and  even  other  patterns 


PENCILS,    ERASERS,    PENS.  5 

are  very  useful.  No.  8,  for  example,  is  useful  for  drawings  in  which  con- 
siderable perspective  is  demanded.  The  advantage  of  this  paper  in  micro- 
scopical drawing  is  that  a  great  number  of  dots  can  be  made  in  a  surprisingly 
short  time,  simply  by  rubbing  a  pencil  back  and  forth  over  its  surface.  Re- 
sults produced  with  pencil  on  five  varieties  of  the  board  are  shown  in  Fig.  3. 
Subsequent  scratching  out  of  these  dots  to  represent  either  uncolored  elements  in 
the  preparation,  or  places  in  it  where  the  transmitted  light  comes  through  clefts 
in  the  tissues,  will  give  remarkably  realistic  effects.  Scratching  is  effected  with 
great  ease  and  accuracy  since  it  merely  consists  in  abrasion  of  the  chalk  sur- 
face of  the  board.  Lines  and  shadows  may  be  strengthened  with  the  pen,  and 
at  need  it  takes  wash  excellently.  A  later  figure  (Fig.  5)  is  given  illustrating 
the  use  of  Ross  board.  Unfortunately,  it  is  expensive.  The  half-sheets  are 
usually  retailed  for  30  cents  and  the  full  sheets  for  50  cents,  and  neither  of 
these  is  very  large. 

Pencils. — There  is  hardly  a  limit  to  the  number  of  pencils  which  can  be 
used  to  advantage,  but  for  all  practical  purposes  three  of  varying  degrees  of 
softness  will  suffice.  Again,  several  firms  manufacture  pencils  of  repute,  but 
for  the  sake  of  simplicity,  there  need  be  mentioned  here  only  the  well-known 
drawing  pencils  made  by  Faber  and  the  Koh-I-Noor,  made  by  L.  &  C.  Hardt- 
muth  in  Austria.  The  grade  known  as  4H  will  be  found  hard  enough  for  the 
finest  and  lightest  of  lines.  HB  is  a  good  grade  for  the  placing  of  outlines, 
while  5B  is  as  soft  and  black  as  usual  work  will  demand  for  the  laying  of  massed 
color.  Even  in  cases  demanding  extreme  hardness,  the  6H  will  be  sufiicient. 
These  pencils  are  usually  sold  at  10  cents  straight. 

Erasers. — These  are  divided  into  two  classes,  one  for  pencil  and  one  for 
pen-work.  A  casual  glance  at  the  supply  of  these  in  any  well-stocked  art  store 
is  sufficient  to  bewilder  the  beginner.  But  one  suggestion  will  be  of  service 
in  selecting  a  pencil-eraser:  Do  not  purchase  a  hard,  colored  article.  Hard 
erasers  destroy  the  surface  of  the  drawing-paper  and  colored  ones,  if  used 
vigorously,  are  very  apt  to  leave  their  own  tint  upon  the  paper.  The  so-called 
"ink-erasers"  had  also  better  be  avoided  entirely,  as  they  either  fail  to  work 
at  all  or  they  sadly  abuse  the  surface  of  the  material  drawn  upon,  x^ny  small, 
well-sharpened  knife-blade,  gradually  and  carefully  applied,  is  much  more  a 
tool  of  choice  in  the  removal  of  ink  than  the  ready-made  erasers.  Good 
pencil-erasers  are  made  by  Hardtmuth,  stamped  with  a  large  H  and  should 
not  cost  more  than  10  cents  at  the  most.  Any  eraser  chosen  should  be  soft 
and  should  wear  rapidly  when  applied  to  the  paper. 

Pens. — Here  again  one  meets  with  a  well  nigh  infinite  assortment.  Still, 
two  pens  of  long-established  worth  will  meet  all  the  demands  laid  upon  the 
beginner,  and  are  described  as  follows:  Joseph  Gillott's  Lithographic  Pen, 
No.  290,  is  one  of  very  fine  point  and,  for  placing  delicate  lines,  it  will  give  entire 
satisfaction.  Its  point,  however,  is  so  flexible  that  an  unsteady  hand  often 
robs  it  of  its  best  work.  Gillott's  Lithographic  Crow  Quill,  No.  659,  is  of  more 
rigidity  and,  in  consequence,  the  beginner  will  do  better  line-drawing  with  it 


6  LABORATORY    GUIDE    FOR    HISTOLOGY. 

than  with  No.  290.  For  stippling,  that  is,  the  placing  of  dots  in  close  proximity, 
this  Crow  Quill  pen  is  so  excellent  that  hardly  another  should  be  named  with 
it  in  the  same  class.  These  pens  are  illustrated  in  Figure  2,  A  and  C,  respec- 
tively. A  third  pen,  made  by  the  same  firm  and  known  as  the  Superfine  Draw- 
ing Pen,  No.  1000,  is  pictured  in  Figure  2,  B,  and  gives,  with  a  steady,  light 
hand,  the  most  delicate  lines  conceivable.  But  since  it  is  many  times  more 
sensitive  than  No.  290,  it  should  not  be  used  unless  the  operator  is  quite  sure  of 
his  touch.  The  cost  of  these  pens  is  as  follows:  Nos.  290  and  659,  50  cents 
a  dozen,  while  a  card  of  12  points,  No.  1000,  is  sold  for  $1.00.  The  Keuffel 
Esser  Co.  also  makes  a  drawing-pen,  known  as  Lithographic  Pen  No.  3205, 
with  which  very  fine  lines  can  be  made  and  it  may  be  used  with  especially  good 
results  in  stipling. 

Pen  Holders. — The  four  varieties  of  pens  above  named  each  include,  on 
the  same  card  with  the  points,  a  pen  holder  especially  adapted  for  the  respective 
pen,  which,  if  properly  used,  will  be  all  that  one  needs.  Still,  the  thinness  of 
these  holders  often  leads  to  a  cramping  of  the  beginner's  fingers.  To  obviate 
this,  one  of  the  many  styles  of  cork  cylinders  may  be  slipped  over  the  holder, 
thus  increasing  its  girth.  Or,  a  holder  closer  resembling  that  of  the  ordinary 
writing-pen  may  be  obtained  for  10  cents  or  15  cents.  This  matter  of  having  a 
thick  pen  holder  should  be  considered  seriously,  for  many  instances  are  met 
where  individuals  are  able  to  do  practically  nothing  with  the  thin  tool,  but  who 
render  quite  satisfactory  drawings  with  one  of  greater  girth. 

PIGMENTS. 

Black  Pigment. — This  may  be  a  fluid,  as  in  the  ordinary  drawing-inks 
and  aqueous  mixtures  of  a  solid  color;  or  in  a  dry  state,  either  as  a  powder  or 
in  mass.  Graphite-filings  and  lamp-black  are  examples  of  powdered  black 
pigment,  and  the  ordinary  water-color  blocks  and  certain  of  the  crayons  repre- 
sent the  same  pigment  in  mass. 

Of  the  ready-mixed  black  drawing 'fluids,  those  made  by  Chas.  M.  Higgins  & 
Co.  will  be  found  very  satisfactory.  They  are  to  be  had  in  two  varieties,  one 
which  will  permit  a  superimposing  of  watery  solutions  upon  them  and  known 
as  waterproof,  and  another  which  would  run  if  so  treated,  the  non-waterproof 
or  general  drawing  ink.  Since  there  is  so  little  choice  between  these  two, 
that  is,  so  far  as  their  drawing  qualities  are  concerned,  one  had  better  buy  the 
first-named  kind,  as  its  waterjiroof  character  is  often  of  distinct  advantage. 
As  manufactured  at  present,  this  ink  has  a  white  label;  the  general  or  non- water- 
proof variety  being  furnished  with  one  of  red.  Both  kinds  sell  at  25  cents  a 
bottle.  Higgins'  ink  can  hardly  be  surpassed  when  used  in  full  strength,  but 
upon  dilution  it  shows  a  brownish  rather  than  a  blackish  tint. 

Where  dilution  of  a  drawing-fluid  is  desired,  Winsor  and  Newton's  Process 
Black,  coming  in  receptacles  of  about  i  oz.  capacity,  will  be  found  to  give  very 
true  intensities  of  black.-     It  is  sold  for  25  cents  a  bottle. 


FIXING.  7 

Graphite-filings  are  to  be  made  as  directed  under  the  remarks  on  black 
and  white  drawing. 

Occasionally  lamp-black  can  be  used,  but  its  tendency  to  show  a  murky- 
brown  upon  thin  distribution  over  the  drawing-paper  often  leads  to  an  unpleas- 
ant result,  for  which  reason  the  beginner,  should  occasion  arise  for  use  of 
powdered  pigments,  is  advised  to  confine  his  work  to  the  graphite  filings. 

Of  the  mass  pigments,  Winsor  &  Newton's  Ivory  Black  ofi'ers  as  many 
virtues  as  any  other  and  is  sold  for  about  25  cents  a  cake. 

Mixing-trays  may  be  dispensed  with  if  one  does  not  desire  to  mix  his  own 
drawing  fluid.  However,  if  this  be  done,  a  porcelain  dish  of  four  compart- 
ments will  give  excellent  service.     It  should  not  cost  more  than  25  cents. 

The  Tortillion,  or  "  blender,"  is  a  tool  practically  confined  to  pencil  drawing 
and  is  pictured  in  Fig.  2,  G.  It  is  a  sort  of  rod,  constructed  of  spirally-wound 
paper  and  comes   in   two  varieties,  gray  and  white,  each  costing   about   the 


C 

Fig.  4. — A  drawing  of  the  style  of  atomizer  used  in  fixing  drawings. 

same,  60  cents  a  gross.  Special  information  concerning  the  tortillion's  use 
can  be  found  in  the  treatment  of  black  and  white  drawing.  Tools  of  similar 
purpose,  called  stomps,  but  constructed  of  different  materials,  such  as  leather, 
are  also  on  the  market.  Still,  these  are  far  too  large,  as  a  rule,  for  any  ordi- 
nary laboratory  work,  and  besides  cost  considerably  more  than  the  paper 
articles. 

Fixing  is  a  process  used  only  where  the  applied  pigments  have  a  tendency 
to  rub  oft"  or  blend  in  handling,  such  as  graphite  and  lamp-black.  Two  articles 
are  necessary — a  fixing  solution  and  an  atomizer.  The  former  is  simply  a 
thin  solution  of  a  resin  (Mastic,  shellac,  damar,  etc.)  and  can  be  obtained  in 
various  quantities,  a  2-oz.  bottle  costing  about  15  cents. 

The  atomizer  consists  of  two  tubes  of  japanned  iron,  a  and  r.  Fig.  4,  linked 
together  by  the  hinge  h.  The  tube  a  is  flattened  from  above  downward  at  its 
free  end,  so  that  it  may  be  held  conveniently  between  the  lips.  The  tube  c 
is  cylindrical  and  is  the  one  whose  distal  end  is  immersed  in  the  fixing  solution. 
Directions  for  the  use  of  both  of  these  articles  can  be  found  in  the  remarks  on 
Fixing  (page  23). 


LABORATORY    GUIDE    FOR    HISTOLOGY. 


COLORS. 

There  are  three  types  of  material  used  in  making  colored  drawings,  namely, 
crayons,  water-colors  and  colored  drawing  inks.  These  present  an  astounding 
variety  and  accordingly  cannot  be  discussed  in  detail. 

Crayons. — A.  W.  Faber's  colored  crayons  are  entirely  reliable,  and  so  much 
more  can  be  done  with  them  than  with  the  cheaper  makes  that  they  are  the  only 
ones  here  described.  The  box  containing  8  colors  costs  75  cents,  but  the 
difference  in  price  between  it  and  the  set  of  twelve  is  not  of  sufficient  advantage 
to  make  up  for  the  loss  in  assortment  of  tints.  The  buyer  may  compose  his 
outfit  according  to  his  own  choice  of  colors,  but  the  following  assortment  will 
be  found  sufficient  for  all  general  purposes: 


Black 

Prussian  Blue 
Light  Blue 
Green  Verditer 


Green  Bice 
Deep  Chrome 
Pale  Chrome 
Roman  Ochre 


India  Brown,  No.  i 
India  Brown,  No.  2 
Vermilion 
Crimson 


Water-colors. — Those  made  by  Winsor  &  Newton  should  be  given  the 
choice  if  one  is  able  to  pay  for  them.  This  expense,  however,  should  not  be 
considered  wherever  a  true  and  permanent  color  is  desired. 

For  general  use  in  the  laboratory,  the  Murillo  Color-box,  in  either  the  65 
cent  or  75  cent  size,  will  give  excellent  results,  and  presents  the  advantage  of 
containing,  aside  from  the  pigments,  a  number  of  brushes  and  a  mixing-tray. 
The  following  list  of  colors  can  be  had  in  the  75  cent  box: 


Vermilion 
Carmine 
Madder  Brown 
Light  Red 
Cobalt 
Ultramarine 


Prussian  Blue 
Indigo 
Ivory  Black 
Emerald  Green 
Vandyke  Brown 


Burnt  Sienna 
Pale  Chrome 
Gamboge 
Indian  Yellow 
Yellow  Ochre 


The  Colored  Drawing  Inks  made  by  Higgins  can  be  recommended;  that 
is,  if  ready-mixed  coloring  fluids  are  to  be  used  at  all.  They  cost  25  cents  a 
bottle  and  are  made  in  the  following  tints: 

Brown 
Indigo 
Violet 


Carmine 

Blue 

Scarlet 

Yellow 

Vermilion 

Green 

Brick -red 

Orange 

The  directions  for  the  use  of  Higgins'  Inks,  either  the  black  or  colored  ones, 
arc  given  in  detail  on  the  wrapper  in  which  the  bottle  is  packed. 

Since  some  of  the  materials  just  described  are  not  absolutely  necessary  for 
drawing  of  microscojjical  preparations,  a  summary  of  essential  articles  is  given 


METHODS    OF    DRAWING.  9 

below,  all  of  which  should  be  in  the  beginner's  possession  before  any  work  of 
this  kind  is  undertaken : 

Drawing-board;  half-dozen  thumb-tacks;  at  least  a  half-dozen  sheets  of  some 
good  drawing-paper;  three  pencils,  of  which  one  must  be  hard,  the  other  medium 
and  the  third  soft;  i  pencil-eraser;  half-dozen  of  Gillott's  drawing  pens,  3  of  No. 
290  and  3  of  No.  659;  i  bottle  of  Higgins'  black  drawing  ink;  a  set  of  colored 
crayons  or  water-colors;  a  good  ruler,  graded  in  millimeters;  scissors  for  cutting 
paper;  and  a  few  blenders.    Other  articles  may  be  obtained  as  occasion  demands. 

METHODS  OF  DRAWING. 

DRAWING    IN    BLACK    AND    WHITE. 

The  drawing  of  microscopical  preparations  falls  primarily  into  two  classes: 
one  done  in  black  and  white  alone  and  the  other  in  color.  The  first  variety  is 
by  far  the  easier  to  execute  and  is  rnore  usually  employed  by  microscopical 


Fig.  5. — Detail  from  the  zona  fasciculata  of  suprarenal  gland,  human,  and  magnified 
about  750  diameters.  An  example  of  line  and  dot  drawing,  and  also  illustrating  what  can 
be  done  with  No.  27  Ross  Board. 

workers.  For  these  reasons  the  use  of  colors  will  be  described  later  and  in  far 
less  corresponding  detail. 

Four  methods  of  distributing  the  pigment  may  be  used,  viz.,  in  dots,  in 
lines,  in  masses,  and  by  combining  two  or  all  of  these. 

Dots  are  placed  at  will  or  according  to  the  surface  of  the  material  drawn 
upon.     If  a  pencil  be  drawn  over  any  rough  surface,  the  graphite  will  cling  to 


lO 


LABORATORY    GUIDE    FOR   HISTOLOGY. 


only  the  projecting  portions,  the  spaces  between  remaining  unaffected.  In 
view  of  this,  a  vast  variety  of  drawing-papers  is  manufactured,  the  surfaces 
of  which  consist  of  more  or  less  minute  elevations"'and  depressions.  Of  all 
these,  as  remarked  in  the  description  of  materials,  only  one  finds  extensive  use 
in  microscopical  illustration,  the  Ross  stipple  board. 

Fig.  5  shows  a  drawing  made  on  No.  27,  Ross  stipple  board,  and  illustrates 


Fig.  6.— Cells  fro 
500 


ells  from  the  pigmented  stratum  of  the  retina  of  rabbit,  enlarged  about 
times;  given  to  illustrate  true  dot-drawing  upon  a  smooth  paper. 


how  dots  may  be  made  according  to  the  nature  of  the  surface  drawn  upon. 
At  a  and  h,  this  point  is  clearly  pictured.  Then  again,  dots  may  be  made 
entirely  according  to  the  will  of  the  operator;  that  is,  each  dot  is  made  by  a 
raising  and  a  touching  of  the  drawing  tool  to  the  surface.  A  drawing  so 
executed  is  represented  by  Fig.  6. 

While  this  latter  figure  does  show  a  subject  in  which  pure  dot-drawing  is  not 
only  permissible  but  imperative,  it  is  not  a  very  usual  necessity  throughout 


Fig.  7.- — Detail  from  precipitation  preparation  of  biliary  capillaries,  liver  of  rabbit, 
enlarged  about  300  times.     An  illustration  of  pure  line-drawing. 


courses  of  laboratory  work.     Only  when  dots  of  a  marked  lack  of  uniformity 
of  distribution  are  required  is  it  necessary  to  place  them  in  this  way. 

Lines  are  always  drawn  according  to  the  will  of  the  worker.  They  are 
likewise  seldom  the  sole  method  of  expressing  a  microscopical  subject,  although 
quite  without  a  substitute  in  parts  of  all  ordinary  drawings.  Fig.  7,  however, 
illnstrates  a  case  where  pure  line-drawing  is  the  only  way  to  tell  the  story. 


MASSES.  II 

Masses  are  done  either  by  the  use  of  a  fluid  pigment  and  a  brush,  by  going 
over  the  surface  carefully  with  a  pencil  until  it  is  completely  covered  with 
graphite  or  by  spreading  evenly  some  powdered  pigment  with  a  tightly  rolled 
blender  of  paper  or  leather.  In  certain  instances,  very  true  pictures  may  be 
made  by  the  exclusive  use  of  mass,  as  illustrated  by  Figure  8;  but,  it  is 
more  often  a  feature  rather  than  the  whole  of  a  drawing. 

Combination  of  two  or  all  the  preceeding  styles  is  the  commonest  way  of 
drawing  microscopical  preparations,  and  that  each  process  may  be  understood, 
a  drawing  will  be  described  which  consists  of  dots,  lines  and  masses  in  propor- 
tion to  the  demands  of  the  selected  subject. 

A  very  important  preliminary  to  starting  a  drawing  of  this  kind  is  to  care- 
fully consider  the  arrangement  of  its  larger  elements.  Never  place  an  ample 
blood-vessel,  a  sharply  circumscribed  group  of  cells,  lobes  of  a  glandular  organ. 


Fig.  S. — Silk  fibers,  enlarged  about  300  times.     An  illustration  of  pure  mass-drawing. 

or,  in  short,  any  conspicuous  feature  exactly  in  the  center  of  the  drawing-field. 
A  certain  stiffness  results  if  this  is  done  and  every  means  should  be  employed 
to  avoid  a  mechanical  effect  untrue  of  the  preparation. 

It  happens  now  and  then,  too,  that  one  has  come  to  an  advanced  stage  in  the 
drawing  before  it  is  observed  that  some  imperfection  of  the  drawing-paper  occu- 
pies exactly  the  space  that  should  be  filled  by  a  feature  of  the  drawing.  There- 
fore, only  the  best  paper  should  be  used,  and  even  this  must  be  examined 
closely  to  avoid  the  appearance  in  the  illustration  of  specks,  stains,  breaks  in 
the  surface  and  other  defects. 

Again,  it  is  very  essential  that  the  field  to  be  drawn  be  carefully  chosen. 
Foreign  particles  or  artifacts  produced  by  the  treatment  in  preparing  the  speci- 
men may  be  present,  or,  it  may  happen,  that  certain  gross  features  of  the  prep- 
aration   being  drawn  bear  a  close  resemblance  to  some  familiar  or  grotesque 


12  LABORATORY    GUIDE    FOR   HISTOLOGY. 

form  in  macroscopic  nature.  Rudimentary  faces,  domestic  animals,  insects, 
etc.,  are  occasionally  simulated  with  such  out-spoken  likeness,  that  they  appear 
more  noticeably  in  the  finished  drawing  than  the  histological  details  it  was  de- 
sired to  present.  Accordingly,  that  portion  of  the  preparation  where  this  unfor- 
tunate feature  appears  should  be  discarded  for  another.  If  this  is  not  allow- 
able, the  preparation  should  be  rotated  this  way  and  that  until  this  similarity 
is  least  evident.  An  instance  is  recalled  where  a  professional  artist  had  failed 
to  examine  a  preparation  of  digested  tissue  in  regard  to  this  point,  and  it  was 
not  until  his  drawing  had  been  published  that  he  remarked  the  all-to-life-like 
resemblance  to  a  well-fed  flea  of  a  somewhat  centrally-placed  mass  of  connec- 
tive tissue.  By  turning  the  preparation,  from  which  this  drawing  was  made, 
about  1 80  degrees,  this  unwelcome  likeness  dwindled  to  its  faintest.  It  would 
have  been  less  noticeable  as  well  had  it  not  occupied  a  central  position. 

Magnification. — The  purpose  of  a  drawing,  naturally,  may  be  as  varied  as 
investigation  itself.  But,  in  another  direction,  the  purpose  of  an  illustration  is 
quite  limited;  that  is,  to  show  the  structures  in  correct  proportions  under  the 
magnification  to  which  the  preparation  examined  has  been  subjected.  If  the 
object  is  enlarged,  say  30  diameters,  its  larger  features  will  be  much  more 
prominent  to  the  student  than  the  minute  ones.  If  the  same  object  be  magni- 
fied 1500  times,  however,  its  larger  features  will  vanish  and  those  of  minute 
dimensions  now  play  the  chief  part.  The  matter  of  relative  size  of  parts  has 
always  to  be  borne  in  mind,  and  frequently  a  sense  of  proportion  has  to  be 
cultivated.  Between  these  two  extremes  of  magnification,  there  is  a  stage 
where  neither  minute  nor  gross  relations  so  greatly  dominate  the  picture, 
and,  fortunately,  it  is  with  this  intermediate  level  that  beginners  have  most  to 
do.  Size  distortion  must  always  be  avoided.  How  unnatural  it  would  be  to 
draw  outlines  at  a  magnification  of  200  and  to  fill  in  with  details  of  twice 
that  enlargement  A  certain  modification  of  this  last  statement  is  occasionally 
allowable,  as  explained  under  the  remarks  on  Detail. 

The  Outline. — There  is  no  time  in  the  history  of  a  drawing  when  more 
thought  and  observation  is  necessary  than  at  the  placing  of  its  outline.  As 
far  as  appearances  go,  the  outline  plays  but  a  secondary  part  in  the  completed 
picture,  yet,  it  must  not  be  forgotten,  that  it  is  in  fact  the  frame-work  upon 
which  the  whole  structure  rests.  A  good  outline  may  redeem  bad  finish,  but  no 
amount  of  excellent  finish  can  save  a  picture  that  has  been  incorrectly  outlined. 

The  pencil  used  for  this  purpose  should  be  well  sharpened  and  of  medium 
grade.  HB  will  be  found  quite  satisfactory.  Many  beginners  make  the  error 
of  using  a  very  hard  pencil  for  outline  work.  It  is  quite  true  that  an  unsteady 
hand  can  make  finer  lines  with  a  hard  than  a  soft  pencil,  but  an  unsteady  hand 
is  apt  to  be  a  heavy  one  as  well,  and  at  the  same  time  that  a  line  is  being  made 
the  surface  of  the  paper  is  being  scratched,  a  fact  not  realized  until  erasure  is 
attempted.  And  erasure  will  be  frequently  resorted  to  during  the  first  efforts, 
because  of  false  drawing.  Therefore,  every  precaution  should  be  taken  to 
avoid  making  lines  that  cannot  be  erased  with  ease.     Unless  great  pressure  be 


THE    OUTLINE. 


13 


put  upon  an  HB  pencil,  its  use  will  be  unattended  with  deep  indentation  of  the 
paper  or  a  scratching  of  it. 

Before  beginning  the  outline  proper  in  making  Figure  9,  the  limits  of  the 
drawing -field  were  placed,  a,  indicating  the  lower  one.  These  limits  can  be 
placed  according  to  the  choice  of  the  operator  or  the  demands  of  the  subject; 
but  the  quadrangular  style,  as  here  pictured,  enjoys  at  present  considerable 
favor.  Frequently  drawings  of  irregular  boundary  are  made  (Fig.  6)  and  then 
no  limiting  lines  are  necessary.  ■ 

After  placing  the  limits  of  the  drawing,  a  careful  attempt  should  be  made 
to  locate  some  tissue-element  that  passes  approximately  through  either  the 


Fig.  9. — Taken  from  the  human  submaxillary  gland,  enlarged  125  diameters, 
to  show  the  different  steps  in  making  a  microscopical  illustration. 


Given 


length  or  breadth  of  the  area.  If  such  cannot  be  found,  then  let  some  promi- 
nent feature  be  sketched.  Since  all  subsequent  outhnes  are  placed  with  con- 
stant reference  to  these  first  features,  they  may  well  be  termed  trunk-lines,  and 
as  such  will  be  spoken  of  in  the  following  description.  The  trunk-line  of  Fig.  9 
was  taken  from  a  roughly,  linear  mass  of  connective  tissue.  Irregularly 
Y-shaped,  its  stem  reaches  the  lower  limit  of  the  picture  at  b,  and  its  limbs  are 
cut  by  the  upper  and  right  margins  at  c  and  d  respectively.  Since  this  Y-shaped 
mass  of  connective  tissue  was  drawn  in  only  as  a  single  line,  naturally  no  attempt 
was  made  to  indicate  its  exact  width  or  special  characteristics;  merely  its  posi- 


14  LABORATORY    GUIDE    FOR   HISTOLOGY. 

tion  in  the  selected  field  and  its  curves  and  angles  were  noted.  The  object  of  the 
trunk-line  is  to  give  the  observer  some  fixed  point,  from  which  he  can  proceed 
to  place  the  more  definite  outlines  of  the  subjective  features  in  the  same  relative 
size  and  position  which  they  possess  in  the  preparation.  This  is  a  very  impor- 
tant step,  and  while  an  expert  might  ignore  it  entirely,  the  beginner  will  find 
such  a  line  of  great  service  toward  giving  the  drawing  its  proper  proportion. 

From  this  Y-shaped  connective-tissue  mass,  it  was  observed  that  smaller 
branches  further  subdivided  the  subjective  features,  and  these  were  hence 
sketched  in  as  elaborations  of  the  trunk-line.  Such  may  be  seen  at  e  and  /. 
These  fines  were  then  utilized  in  the  following  manner  to  outline  the  remaining 
tissue  elements. 

At  g,  the  outlines  of  a  somewhat  tangentially-cut  duct  can  be  seen,  and  in  the 
preparation  its  right  limit  ran  about  parallel  with  that  portion  of  the  left  limb 
of  the  Y-shaped  connective-tissue  mass  included  between  the  point  h,  where 
an  interlobular  septum  joined  it,  and  the  point  i,  where  this  limb  bent  sharply 
toward  the  left.  Further,  this  right  limit  of  the  duct  g,  was  observed  to  be  as 
far  to  the  left  of  the  extreme  right  limit  of  the  connective-tissue  mass  as  the 
lumen  of  the  blood-vessel    ],  was  wide. 

Looking  at  the  long  axis  of  the  section  of  the  duct  g,  it  was  seen  that  it 
inclined  upward  at  about  the  same  angle  as  that  portion  of  the  interlobular 
septum  which  is  indicated  at  k.  This  latter  observation  determined  the  direc- 
tion of  the  duct's  long  axis  but  not  its  length.  To  establish  this,  attention  was 
directed  to  the  right-hand  limit  of  the  duct,  which  had  already  been  sketched. 
The  length  of  this  limiting  line  was  picked  up,  as  it  were,  in  the  eye  and  then 
laid  upon  the  long  axis  of  the  duct  in  much  the  same  manner  as  a  carpenter 
uses  his  rule.  By  means  of  this  comparison  it  was  determined  that  the  long 
axis  of  the  duct  was  about  three  times  as  long  as  the  line  used  as  a  measuring 
unit,  and  a  point  was  put  down  at  that  distance  to  mark  off  the  extreme  left  limit 
of  the  duct.  This  left-hand  limit  was  sharply  bent  at  about  its  middle,  and  by 
drawing  an  imaginary  line  between  the  ends  of  this  bend,  the  left  limit  was  found 
to  be  about  the  same  length  as  the  right  limit.  Near  its  middle  portion  the 
duct  was  constricted  to  about  three-fourths  the  breadth  of  the  right-hand  limit. 
With  the  dimensions  recorded,  the  duct  was  then  outlined,  giving  particular 
attention  to  its  inner  and  outer  contour  as  formed  by  cellular  limits.  The 
next  feature  sketched  in  was  the  large  blood-vessel,  /.  The  same  methods  of 
placing  it  in  proper  proportion  were  employed  as  those  described  in  sketching 
the  duct,  g.  Thus,  three  features  were  gained  as  measuring  units:  the  Y-shaped 
connective-tissue  mass,  the  tangentially-cut  duct,  and  the  large  blood-vessel. 
Constantly  using  these  as  guides,  the  surrounding  tissue  elements  were  outlined, 
each  being  added  on  by  continual  intercomparison,  and,  in  this  manner,  were 
placed,  if  not  in  unerring  size-ratio,  at  least,  in  fair  proportionate  likeness  to 
the  actual  specimen. 

It  has  taken  some  space  to  describe  this  process  of  outlining  in  proper 
proportion,  but  as  soon  as  the  beginner  has  grasped  the  idea,  he  will  use  it  with 


THE    GROUND    COLOR.  1$ 

considerable  speed  and  exactness;  in  fact,  it  shortly  becomes  an  almost  uncon- 
scious procedure. 

The  Ground  Color. — By  this  term  is  meant  an  even  mass  of  faint  color 
distributed  over  the  whole  drawing  except  where  the  transmitted  light  from  the 
reflecting  mirror  of  the  microscope  passes  unimpeded  through  actual  spaces  in 
the  tissue.  If  those  spaces  are  small,  the  ground  color  may  be  carried  over 
them  without  hesitancy;  but  if  they  are  conspicuous,  as  the  interlobular  area,  vi, 
in  Fig.  9,  the  ground  color  must  be  omitted.  The  ground  color,  as  it  was  laid 
in  Fig.  9,  is  left  unchanged  in  that  portion  of  the  illustration  included  within 
the  bracket  2.  Bracket  i,  shows  a  section  representing  the  outline  alone. 
This  ground  color  is  to  the  various  shades  of  the  picture  what  the  trunk-line 
is  to  the  sketching  in  of  the  tissue  elements.  It  holds  these  shades  together  and 
is  used  as  the  unit  of  their  intensities.  This  point  will  be  more  fully  explained 
at  the  stage  of  Differential  Color. 

There  are  three  methods  in  common  use  in  laying  the  ground  color:  (i)  by 
lightly  drawing  a  pencil  back  and  forth  over  the  paper  until  an  even  coat  of 
graphite  is  obtained;  (2)  by  charging  a  tortillion  with  some  powdered  pigment, 
usually  graphite,  and  carrying  it  over  the  paper  with  a  light  touch  until  a  uni- 
form mass  of  color  is  effected;  and  (3)  by  brushing  on  some  fluid  pigment,  as  a 
rule,  an  aqueous  solution  of  black  water-color,  process  black  or  drawing  ink. 

1.  If  the  pencil  be  chosen  with  which  to  lay  the  ground  color,  it  should 
be  neither  too  hard  nor  too  soft.  A  very  hard  pencil  requires  considerable 
pressure,  while  a  soft  one  must  be  handled  with  extreme  delicacy  to  obtain  an 
even  mass  of  pigment.  HB,  Koh-I-Noor,  or  Faber  will  be  found  a  satisfactory 
grade  of  pencil  at  this  stage  of  the  drawing.  Before  commencing  the  procedure, 
however,  the  pencil's  point  must  be  dragged  back  and  forth  over  some  rough 
scratch-paper,  in  order  to  blunt  it,  as  a  sharp  point  is  apt  to  give  a  lot  of  fine 
lines,  rather  than  an  even  mass  of  color,  as  well  as  delay  the  process.  Should 
lines  occur,  in  spite  of  the  mentioned  precaution,  they  may  be  blended  into  a 
fairly  homogeneous  mass  by  rubbing  over  them  with  a  clean  tortillion;  that 
is,  if  they  have  not  been  put  in  too  heavily.  The  beginner  will  probably 
find  the  pencil,  with  subsequent  use  of  the  tortillion,  by  far  the  most  satisfactory 
method  of  laying  the  ground  color,  since  with  them  there  is  less  danger  of  its 
overlapping  its  proper  boundaries.  The  charged  tortillion  and  the  brush  can 
be  used  with  good  results  only  after  considerable  familiarity  with  their  particular 
characteristics  has  been  gained. 

2.  If  powdered  graphite  be  the  pigment  used  to  lay  the  ground  color,  the  em- 
ployment of  the  tortillion  is  necessary.  The  graphite  is  prepared  in  the  following 
manner:  a  file  of  fine  tooth  is  held  at  an  angle  over  a  small  receptacle  or  piece 
of  paper,  and  a  pencil  of  moderate  softness,  HB,  for  example,  is  dragged  up  and 
down  upon  the  file.  Into  these  filings  the  tortillion  is  now  rubbed,  is  then 
gently  tapped  with  the  finger  to  remove  any  superfluous  pigment  clinging  to  it, 
and  is  finally  gently  rubbed  over  the  scratch-paper,  turning  it  meanwhile,  in 
order  to  distribute  the  graphite  evenly  upon  its  point.      The  tortillion,  thus 


1 6  LABORATORY   GUIDE    FOR   HISTOLOGY. 

charged,  is  now  to  be  used  on  the  drawing  exactly  as  a  pencil.  If  the  ground 
color  shows  streaks,  it  may  be  converted  into  a  uniform  mass  by  rubbing  over 
it  with  an  uncharged  tortillion.  It  will  be  found  that  the  tortillion's  point,  after 
some  use,  has  become  worn  off  and  quite  flexible,  an  occurrence  which  rules 
out  its  further  employment  in  the  fine  work.  For  drawings  of  small  area  and 
requiring  a  light  shade  of  the  ground  color,  the  necessary  graphite  may  be 
made  available  by  simply  rubbing  the  point  of  the  HB  pencil,  flat-wise,  over 
an  area  of  an  extra  piece  of  drawing  board  until  the  surface  is  densely  black 
(thus  obviating  the  need  of  a  file)  and  applying  the  tortillion  to  this  surface. 

3.  With  a  brush  and  fluid  pigment  the  best  ground  color  can  be  laid.  The 
brush,  however,  is  such  a  stranger  in  the  hands  of  most,  that  the  beginner  sel- 
dom accomplishes  good  work  with  it.     Practice  will,  nevertheless,  enable  one 


Fig.  10. — Illustrating  the  method  of  preparing  fluid  pigments  from  the  solid  block. 

to  pursue  the  method  with  increasingly  better  results,  and  because  of  its 
greater  possibilities,  its  use  is  strongly  recommended.  As  pigment,  either  a 
solid  or  fluid  variety  may  be  employed,  and  of  these  Winsor  &  Newton's 
Ivory  Black  and  Process  Black  may  serve  as  respective  examples.  A  solution 
of  Ivory  Black,  from  the  solid  cake,  is  prepared  as  follows,  illustrated  by  Fig.  10: 
The  color-block,  a,  is  firmly  held  between  the  thumb  and  first  two  fingers 
and  then  rubbed  vigorously  in  a  few  drops  of  water  placed  in  one  of  the  com- 
partments of  the  mixing-dish  h.  Gradually  the  water  will  take  up  the  color 
until  it  assumes  a  deep  black  tone.  Then  the  trituration  of  the  color  should  be 
stopped  and  clear  water  added  to  the  fluid  in  the  mixing-dish  until  it  is  about 
twice  as  dark  as  the  tint  desired  for  the  ground  color.  The  brush  is  charged 
with  this  fluid  simply  by  immersing  it  in  the  same  and  allowing  it  to  draw  as 
much  of  the  pigmented  water  as  it  will.  Here  the  beginner  is  apt  to  make  a 
mistake  by  freeing  the  brush  of  some  of  its  charge  until  its  point  is  finely  tapered. 


THE    GROUND    COLOR. 


17 


This  should  not  be  done,  as,  in  that  case,  enough  fluid  does  not  remain  in  the 
brush  to  permit  the  laying  of  an  even  mass  of  color.  If  the  brush  has  been 
charged  properly,  an  excess  of  fluid  will  be  left  in  its  trail  over  the  drawing,  and, 
since  the  color  has  been  prepared  twice  the  intensity  of  the  tone  desired,  it  will 
seem  much  too  dark.  No  anxiety  should  be  felt  at  this,  however,  as  the  following 
step  corrects  the  apparent  mistake:  The  brush  is  sharply  shaken  over  a  hopper 
until  relieved  of  the  greater  part  of  its  charge  of  color,  which  is  evidenced  by  the 


a- 


Fig.  II. — Illustrating  the  method  of  removing  the  excess  of  color  in  the  process  of  using 
fluid  pigment  for  placing  the  ground-color  or  differential  color  of  a  drawing. 


reappearance  of  the  tapered  point.  The  exhausted  brush  is  now  to  be  carried 
over  the  area  on  the  drawing  where  the  excess  of  fluid  presents,  and,  just  as 
the  hairs  absorbed  the  pigmented  water  from  the  mixing-tray,  they  now  do  the 
same  from  the  drawing.  Since  only  a  portion  of  the  suspended  pigment  has 
had  time  to  settle  to  the  surface  of  the  drawing,  this  process  of  removing  the 
excess  of  coloring  fluid  will  leave  a  much  lighter  tint  than  one  would  expect  to 
follow  the  use  of  a  color  so  dark.  Accordingly,  it  must  be  borne  in  mind  that 
the  pigment  should  always  be  prepared  considerably  darker  than  the  tint 


1 8  LABORATORY    GUIDE    FOR   HISTOLOGY. 

desired  for  the  ground  color.  To  determine  just  how  dark  this  pigment  should 
be  during  the  mixing,  a  few  tests  on  scratch-paper  similar  to  the  f)aper  drawn 
upon  will  be  necessary  for  the  beginner.  Fig.  1 1  gives  an  idea  of  how  the  sur- 
plus of  coloring  fluid  is  removed  from  the  drawing.  The  brush,  a,  has  been 
exhausted,  as  is  shown  by  its  finely  tapered  point,  and  is  about  to  be  plunged 
into  one  of  the  drops  of  excess  coloring  fluid,  b.  C,  represents  areas  that  have 
already  been  relieved  of  their  surplus  color.  The  object  in  following  this 
procedure,  instead  of  merely  painting  over  the  desired  surfaces  with  a  partially 
exhausted  brush,  as  the  beginner  is  prone  to  do,  is  to  obtain  an  even  distribution 
of  the  ground  color,  and  it  must  be  realized  that  this  is  attained  by  the  settling 
of  the  suspended  particles  of  pigment  upon  the  surface  of  the  paper  from  the 
excess  of  fluid  above.  Therefore,  care  should  be  taken  that  the  excess  remains 
equal  lengths  of  time  upon  the  paper.  If  the  areas  to  be  colored  are  small 
and  individual,  the  color  may  be  placed  upon  three  or  four  at  a  time  and  the 
surplus  removed  in  the  order  in  which  it  was  put  down. 

Proceeding 'as  directed  above,  the  ground  color  was  then  laid  on  in  Fig.  9, 
a  portion  of  which,  as  remarked,  is  still  to  be  seen  in  that  part  of  the  picture 
included  within  the  bracket  2. 

Differential  Color. — This  stage  of  the  drawing  is  one  generally  attended 
with  as  much  difficulty  for  the  beginner  as  even  the  proper  placing  of  outlines, 
and  it  is  here  that  most  drawings  depart  furthest  from  the  specimen  under 
observation.  By  differential  color  is  meant  that  varying  intensity  of  shading, 
which  serves  to  show  the  different  tints  in  stained  preparations  on  the  one  hand, 
or,  on  the  other,  the  relative  opacity  of  structures  in  unstained  ones.  To  illus- 
trate this  point,  attention  is  directed  to  that  portion  of  Fig.  9  included  within 
the  bracket  3.  There  it  may  be  seen  that  the  only  uncolored  areas  are  where 
there  is  no  tissue  to  obstruct  the  rays  of  transmitted  light,  as  in  the  lumen  of 
the  duct,  n.  Proceeding  from  light  to  dark,  the  first  mass  of  color  to  attract 
attention  is  the  remnants  of  the  ground  color,  as  at  0.  The  next  darkest  shade 
is  to  be  found  in  the  ducts,-  as  at  p;  and  the  darkest  of  all  the  tones  seen  in  the 
field,  included  by  the  bracket  3,  is  that  representing  the  serous  alveoli,  as  at 
g.  The  darkest  differential  shade  in  the  whole  drawing,  however,  is  shown 
in  the  connective-tissue  fibrils,  the  connective-tissue  nuclei,  protoplasmic 
granules  and  reticulated  basement  membranes,  all  of  which  are  included  within 
bracket  4.  But  since  this  dead  black  color  belongs  to  the  stage  of  Detail, 
it  will  be  postponed  until  that  subject  is  discussed. 

Before  laying  the  differential  color  on  the  drawing,  according  as  the  tissue 
is  stained  or  unstained,  the  respective  tints  or  degrees  of  opacity  in  the  prepa- 
ration must  be  closely  scrutinized,  and  the  point  settled  how  to  express  them 
in  black  or  in  some  degree  of  its  intensity.  In  the  preparation  from  which 
Fig.  9  was  drawn,  the  following  colors  were  observed:  The  lightest  color 
was  found  to  be  a  very  faint,  cloudy  blue  presented  by  the  mucous  cells,  r. 
The  next  lightest  was  a  brick-red  in  the  connective  tissue  and  ducts,  as  at  s 
and  i,  respectively.     Following  that,  the  serous  alveoli,  as  at  u,  showed  the  next 


Fig.  12. — Scheme  showing  the  relations  of  the  principal  colors  to  each 
other.  Inner  circle,  Primary  Colors;  middle  circle,  Secondary  Colors; 
outer  circle,  Tertiary  Colors. 


DIFFERENTIAL    COLOR.  I9 

degree  of  shading,  a  reddish  purple,  while  some  of  the  connective-tissue  nuclei 
gave  the  darkest  tone  of  all  in  the  way  of  a  heavy  hematoxylin  stain,  bluish 
purple,  V. 

Though  the  subject  of  color  is  discussed  later,  it  is  right  here  very  advis- 
able to  devote  some  time  to  the  science  of  color,  as  its  elementary  principles 
will  help  the  beginner  to  make  better  drawings  in  black  and  white. 

Fig.  12  shows  a  number  of  colors  arranged  concentrically  in  three  circles. 
The  three  colors  included  in  the  central  circle  are  yellow,  red  and  blue,  called 
primary  colors,  since  they  cannot  be  obtained  by  mixing  other  tints.  The  next 
circle  includes  thie  secondary  colors;  that  is,  those  obtained  by  mLxing  the  two 
adjacent  primaries,  thus:  blue  mixed  with  yellow  gives  green;  yellow  mixed 
with  red  gives  orange,  and  red  mixed  with  blue  gives  purple.     The  outermost 


Fig.  13. — Companion  scheme  to  Fig.  12.  The  different  shades  of  black  comprising 
the  three  circles  are  intended  to  represent  in  terms  of  black  and  white,  the  shade- 
value  of  the  respective  colors  presented  in  Fig.  12. 

circle  contains  the  tertian,-  colors,  which  are  obtained  by  mixing  the  two  adjacent 
secondaries,  thus:  green  with  orange  gives  olive,  orange  with  purple  gives  brown, 
and  purple  with  green  gives  gray. 

Directing  attention  to  the  primary  colors,  it  is  easily  e\'ident  that  yellow 
gives  the  impression  of  containing  more  light  in  it  than  either  red  or  blue,  while 
blue  is  the  darkest  of  the  three.  For  this  reason  yellow  is  spoken  of  as  light, 
blue  as  shadow,  while  red  is  taken  as  the  symbol  of  color.  Among  the  second- 
ary- colors,  orange  is  the  lightest,  because  it  is  produced  by  mixing  the  two 
lightest  primaries,  yellow  and  red.  Green  is  not  so  light  as  orange,  due  to  its 
component  of  blue.  Purple  is  the  darkest  secondary  color,  as  it  has  no  yellow 
integer.  Of  the  tertian,^  colors,  olive  is  the  lightest,  since  it  contains  two 
parts  of  yellow  coming  from  the  colors  used  to  make  it,  orange  and  green,  and 
only  one  part  of  blue,  derived  from  the  green.     Brown  is  darker  than  olive. 


20  LABORATORY    GUIDE    FOR    HISTOLOGY. 

since  by  analyzing  its  component  colors,  orange  and  purple,  it  is  seen 
that  one  part  of  yellow  has  been  supplanted  by  an  integer  of  red,  purple 
containing  no  yellow.  Gray  is  the  darkest  of  the  tertiary  series,  since  in- 
spection of  its  integral  colors,  green  and  purple,  will  show  that  it  contains 
two  parts  of  blue,  which  represents  more  shadow  than  exists  in  either  olive 
or  brown. 

Now,  comparing  the  colors  in  the  three  rings,  one  with  the  other,  in  regard 
to  their  relative  lightness  and  darkness,  it  is  readily  seen  that  yellow  is  the 
lightest,  orange  the  next  and  olive  the  next.  Turning  to  the  other  extreme, 
blue  is  found  to  be  the  darkest  color,  purple  follows  second,  while  gray  is  the 
third  in  shadow  intensity.  By  analysis  of  these  colors,  according  to  the  number 
of  yellow  units  they  contain,  on  the  one  hand,  and  the  number  of  blue  units, 
on  the  other,  it  can  easily  be  explained  why  they  bear  to  each  other  this  respec- 
tive relationship  of  light  and  shadow. 

This  discussion  of  color  science  has  been  given  to  show  the  means  by  which 
color  proper,  or  color  values,  may  be  translated  into  black  or  some  degree  of 
its  intensity.  It  is  obvious,  of  course,  that  this  cannot  be  done  so  perfectly 
that  mere  inspection  of  these  varying  degrees  of  black  will  reveal  exactly  the 
colors  they  were  designed  to  represent,  nor  is  this  at  all  necessary  for  our  pur- 
pose. It  is,  however,  quite  possible  to  make  a  drawing  in  black  and  various 
degrees  of  its  intensity  in  which  the  color  differentiations  of  the  tissue  elements 
will  be  nearly  as  sharply  distinguished  as  in  the  preparation  under  the  micro- 
scope. To  illustrate  this,  attention  is  called  to  Fig.  13.  Here  again  are 
three  concentric  rings.  In  the  inner  circle  the  lightest  area  is  pure  white  and 
represents  yellow;  the  darkest  area  stands  for  blue,  while  the  remaining  one 
represents  red.  In  the  second  circle,  the  lightest  part  corresponds  to  orange, 
the  darkest  represents  purple,  and  the  remaining  area  stands  for  green.  In  the 
outer  circle,  the  lightest  area  represents  olive,  the  darkest  one,  gray,  while  the 
remaining  area  represents  brown.  As  already  remarked,  a  critical  examination 
of  these  varying  degrees  of  black  would  surely  fail  to  distinguish  the  exact 
color  each  is  intended  to  represent;  but  by  comparing  them  with  the  colors  in 
Fig.  12,  which  occupy  the  same  relative  positions,  a  marked  similarity  will  be 
found  between  the  integers  of  both  schemes;  that  is,  as  far  as  light  and  shadow 
are  concerned.  For  example,  the  lightest  color  in  Fig.  12  is  yellow,  while  the 
lightest  area  in  Fig.  13  occupies  the  same  relative  position.  Further,  blue  is  the 
darkest  color  in  Fig.  12,  and  in  the  same  relative  position  is  to  be  found  the 
darkest  area  of  Fig.  13.  Such  relations  will  be  found  to  tally  throughout  the 
balance  of  both  figures. 

For  the  practical  application  of  these  relationships,  suppose  a  preparation 
which  has  been  subjected  to  the  action  of  two  stains,  blue  and  yellow,  is  to  be 
represented  in  a  black  and  white  drawing.  Reference  to  Figs.  12  and  13 
shows  that  blue  is  many  times  darker  than  yellow,  so  the  two  differently  stained 
tissues  would  be  accordingly  differentiated  in  the  drawing  by  the  use  of  a 
strong  degree  of  black  for  the  blue  and  a  much  weaker  degree  for  the  yellow. 


THE    STAGE    OF    DETAIL.  21 

This,  however,  may  be  done  only  in  instances  where  the  blue  and  the  yellow 
are  in  sufi&cient  quantity  to  be  considered  approximately  pure. 

A  condition  found  quite  commonly  in  stained  preparations,  unfortunately, 
brings  a  difficulty  into  the  matter  not  to  be  solved  by  the  use  of  constant  rules. 
This  difficulty  is  the  one  of  color  dilution,  and  must  be  met  by  the  student's 
individual  powers  of  interpretation.  True  blue  is  .darker  than  true  red;  but  a 
blue  that  has  been  diluted  to  an  extreme  degree  with  white  light  (decolorized  or 
not  taken  by  the  tissue),  could  not  properly  be  represented  by  a  stronger  in- 
tensity of  black  than  the  one  used  to  represent  a  true  red.  To  illustrate  this,  a 
common  enough  landscape  suffices.  Imagine  the  pale  blue  sky  of  a  day  in  early 
spring,  and,  contrasted  with  it,  the  red  roof  of  a  nearby  house.  If  a  pencil  sketch 
were  to  be  made  of  this  combination,  how  unnatural  it  would  look  if  the  roof 
were  drawn  in  lighter  than  the  sky!  And  diluted  colors — that  is,  very  pale  ones 
— will  probably  be  found  more  often  in  stained  tissue  than  will  colors  of  full 
intensity.  To  satisfactorily  represent  these  in  degrees  of  black,  the  student  is 
thrown  entirely  upon  his  own  resources.  Nevertheless,  he  will  be  better  pre- 
pared to  interpret  the  shade  values  of  different  tints  if  the  foregoing  elemental 
principles  of  color  science  have  been  carefully  considered. 

Turning  back  to  the  drawing  represented  in  Fig.  9,  which  has  been  described 
up  to  the  stage  of  Differential  Color,  the  various  tints  which  were  seen  in  the 
tissue  under  the  microscope  will  be  enumerated  again.  The  lightest  color  was 
a  very  much  diluted  blue,  shown  by  the  mucous  cells;  the  next  Hghtest,  a  brick- 
red  in  the  connective  tissue  and  ducts;  the  next,  a  reddish-purple  in  the  cells 
of  the  serous  alveoli,  and  the  darkest  color  of  all,  a  bluish-purple,  was  found  in 
some  of  the  connective-tissue  nuclei.  With  the  exception  of  the  latter,  these 
colors  were  represented  in  the  drawing  by  various  degrees  of  black,  as  seen 
in  that  portion  of  Fig.  9  included  within  bracket  3.  It  should  be  remembered, 
in  placing  these  shades,  that  the  intensity  of  the  ground  color  must  be  con- 
stantly kept  in  mind,  as  it  is  the  unit  of  shading  in  the  picture.  It  represents, 
as  said  before,  the  lightest  structure  in  the  preparation,  and,  since  the  mucous 
cells  presented  the  lightest  color  to  be  found  in  the  preparation  from  which 
Fig.  9  was  drawn,  the  ground  color  on  these  was  therefore  left  quite  un- 
changed and  all  other  degrees  of  black  were  laid  to  properly  contrast  with 
this  tone.  Thus  the  ground  color  is  to  the  differential  color  what  the  trunk- 
lines  are  to  the  placing  of  the  outline. 

Just  as  m  putting  on  the  ground  color,  the  differential  color  may  be  laid 
either  with  pencil,  pencil  and  tortillion,  with  the  latter  alone  charged  with  pow- 
dered graphite,  or,  with  a  brush  and  fluid  pigment.  The  latter  was  the  method 
used  in  drawing  Fig.  9.  The  same  advantages  which  the  pencil  and  tortillion 
offer  the  beginner  in  placing  the  ground  color  also  hold  good  when  laying  the 
dift'erential  color.  The  charged  tortillion  and  brush  with  fluid  pigment  are  by 
no  means  so  easily  handled.  Both  of  them  are  apt  to  overlap  the  tissue  outlines, 
especially  if  the  areas  thus  treated  are  of  small  extent. 

The  Stage  of  Detail. — This  is  the  period  in  the  history  of  a  drawing  when 


22  LABORATORY    GUIDE    FOR    HISTOLOGY. 

the  final  characteristics  of  the  tissue  elements,  the  details  of  structure,  are 
added.  These  are  shown  in  Fig.  9  at  that  portion,  included  by  bracket  4, 
and  are  seen  to  consist  of  individual  connective-tissue  fibrils,  cell  boundaries, 
protoplasmic  granules  and  nuclei. 

Concerning  what  details  should  be  pictured  and  what  left  out  depends 
entirely  upon  the  purpose  of  the  drawing,  and  thvis  the  amount  and  kind  of 
detail  obviously  will  differ  with  the  special  object  of  the  illustration.  Again, 
granting  that  but  one  drawing  is  to  be  made  of  a  certain  preparation,  as  in 
Fig.  9,  and  that  the  object  of  the  drawing  is  to  give  a  general  idea  of  the  structure 
of  that  preparation,  it  is  then  persnissible  to  slightly  intensify  the  appearance 
of  some  details  which  are  only  imperfectly  seen  at  the  given  magnification. 
For  instance,  the  striations  found  in  the  duct-epithelium  of  Fig.  9,  at  v,  could 
not  be  seen  distinctly  at  the  enlargement  of  125  diameters,  but  their  existence 
and  character  should  be  shown  in  the  general  drawing.  Raising  the  magnifi- 
cation, however,  to  560,  these  markings  could  be  definitely  made  out,  and 
they  were  put  in  as  seen  to  be  arranged  under  this  magnification.  Also,  many 
of  the  connective-tissue  fibrils  were  by  no  means  as  sharply  evident  as  repre- 
sented in  the  drawing;  but,  as  this  one  drawing  is  to  express  a  fairly  compre- 
hensive idea  of  the  tissue  constituents  of  the  preparation,  and  since  increased 
magnification  made  the  fibrils  quite  clear,  no  hesitancy  was  felt  in  making  the 
hbrils  more  apparent  than  they  were  at  an  enlargement  of  125  diameters. 

It  will  be  noted  that  some  of  the  cell  boundaries,  such  as  those  found  in  the 
serous  alveoli,  are  exceedingly  faint.  'This  detail  was  accomplished  not  so 
much  by  the  fineness  of  the  line  as  by  a  dilution  of  the  drawing  fluid.  This 
may  be  resorted  to  successfully  in  many  instances  where  one  wishes  to  represent 
features  but  faintly  seen  in  the  preparation.  Had  it  been  especially  essential  to 
the  purpose  of  the  drawing  to  exagerate  these  cell  boundaries,  such  would  have 
been  done  as  in  the  two  instances  above  mentioned;  but  in  this  case  mere 
indication  of  them  sufficed. 

In  diluting  any  drawing  fluid,  something  should  be  added  that  it  may  have 
sufficient  consistency  to  prevent  the  pigment  granules  gravitating  immediately 
to  the  pen's  point.  The  following  manner  of  dilution  will  be  found  efficient: 
Having  put  a  few  drops  of  ink  or  triturated  water-color  in  the  mixing-dish, 
water  is  added  until  the  desired  intensity  has  been  reached,  and  then,  with  a 
brush  whose  point  has  been  dipped  in  Le  Page's  glue  or  a  10  per  cent,  aqueous 
solution  of  gum  arable,  the  whole  is  thoroughly  mixed.  This  diluted  fluid  is  put 
on  the  pen  with  the  charged  brush.  Concerning  the  choice  of  pens  for  placing 
details,  reference  may  be  made  to  the  pages  dealing  with  drawing  materials. 

Lettering.— The  details  placed,  the  drawing  is  now  finished,  aside  from 
putting  in  the  various  "leaders,"  which  refer  to  structures  discussed,  and 
lettering  them.  These  leaders  may  be  made  either  as  solid  lines  or  broken 
ones,  the  selection  being  left  to  the  operator  with  but  this  one  condition:  neither 
should  be  made  so  thick  that  it  obscures  those  parts  of  the  drawing  through 
whicji  it  passes.     Broken  lines  give  neater  effects  and  obscure  less,  but  they 


LETTERING. 


23 


are  more  difficult  to  make  uniformly.  There  is  a  great  number  of  styles  used 
in  lettering,  and  here  again  but  one  condition  is  imposed — legibility.  One  form 
of  letter  is,  however,  particularly  popular  and  is  very  easily  read,  namely,  the 
so-called  italic.  The  characters  of  this  style  of  letter  may  be  seen  in  the 
following  alphabet  and  numerals: 

Aa,  Bb,  Cc,  Dd,  Ee,  Fj,  Gg,  Hh,  li,  Jj,  Kk,  LI,  Mm,  Nn,  Oo,  Pp,  Qq,  Rr,  Ss, 
Tt,  Uu,  Vv,  Ww,  Xx,  Yy,  Zz,  i,  2,  3,  4,  5,  6,  7,  8,  9,  o. 

The  placing  of  characters  within  the  drawing  on  the  structures  described 
is  to  be  condemned.  This  not  only  obscures  the  detail  but  frequently  occasions 
considerable  annoyance,  as  letters  or  numbers  so  placed  are  difficult  to  find, 
especially  if  the  drawing  is  of  any  size  and  rich  in  detail.  Fig.  9  gives  an 
example  of  lettering,  and  while  the  leaders  are  placed  irregularly  here,  they 


Fig.  14. — Illustrating  use  of  apparatus  and  position  assumed  in  "  fixing"  a  drawing. 

may  often  be  placed  radially  or  even  run  parallel  to  each  other.  At  times, 
however,  parallel  leaders  give  an  effect  of  stiffness  to  the  drawing. 

Fixing. — The  materials  used  in  this  process  have  already  been  described. 
The  process  is  necessary  only  in  those  instances  where  pigments  have  been 
used  that  have  a  tendency  to  rub. 

Fig.  14  shows  the  position  assumed  by  the  operator  when  fixing  a  drawing. 
The  drawing-board,  a,  upon  which  the  illustration,  h,  has  been  fastened  with 
thumb-tacks,  is  held  in  the  right  hand  at  arm's  length  from  the  body.  The 
left  hand  supports  the  bottle  of  fixing  solution,  c,  in  which  the  cylindrical  tube, 
d,  of  the  atomizer  is  immersed,  while  the  flattened  tube,  e,  is  held  firmly  between 
the  lips.  Upon  strong  blowing  through  the  mouth-tube  a  jet  of  air  streams 
swiftly  across  the  upper  end  of  the  tube  resting  in  the  solution,  thereby  causing 
a  reduction  of  pressure  within  it,  which,  in  turn,  causes  the  fluid  to  rise.  When 
this  column  of  fluid  comes  in  contact  with  the  jet  of  air  from  the  mouth-tube, 
it  is  divided  into  a  fine  spray  which  deposits  itself  evenly  over  the  drawing. 
If  the  drawing  be  held  close  to  the  bottle,  where  the  spray  is  more  den-^e.  it  will 


24 


LABORATORY    GUIDE    FOR    HISTOLOGY. 


be  literally  bathed  rather  than  lightly  sprinkled  with  the  fluid.  This  is  a 
condition  to  be  avoided,  since  a  large  quantity  of  fixing  solution  takes  some 
time  to  dry,  leaving,  as  well,  an  eye-trying  gloss  upon  the  picture.  Again,  if 
considerable  graphite  be  present,  a  surplus  of  the  solution  may  carry  it  down 
along  the  picture  giving  it  a  streaky  appearance  upon  drying.  To  obtain  the 
best  spray,  the  mouth-tube  should  be  held  at  nearly  a  right  angle  to  the  immersed 
tube.  A  marked  obtuse  angle  will  result  in  directing  the  jet  of  air  into,  instead 
of  across  the  tube,  or  an  acute  angle,  so  far  away  from  its  upper  end,  that  the 
fluid  will  not  rise.  After  use,  the  atomizer  should  be  shaken  sharply  to  free 
it  of  the  fixing  solution  still  contained  in  the  cylindrical  tube,  for,  if  this  were 
allowed  to  remain,  the  evaporation  of  the  fluid  would  leave  a  plug  of  resin  in 
the  tube's  chamber,  an  obstacle  that  often  causes  considerable  vexation  before 
its  removal  is  accomplished. 


Fig.  15. — Showing  a  method  and  a  form  of  stitch  to  be  used  in  mounting 
drawings  by  sewing. 


Mounting. ^In  common  use  there  are  three  methods  of  mounting  the 
drawings  in  laboratory  papers:  pasting,  sewing,  and  insertion  in  slits.  Each 
has  its  particular  merits,  but  the  last  method  is  least  burdened  with 
disadvantages. 

If  pasting  is  selected,  only  a  fluid  of  rapid  and  effective  adhesive  qualities 
should  be  used,  such  as  Le  Page's  liquid  glue.  If  an  inferior  mucilage  has 
been  chosen,  it  will  take  some  time  to  "  set,"  and  even  then  there  is  no  guarantee 
that  the  drawing  will  hold  to  the  mount.  No  attempt  should  be  made  to  cover 
the  whole  back  of  the  drawing  with  glue,  as  in  this  instance  it  will  be  found 
only  too  often  that  the  drawing  upon  drying  has  acquired  unsightly  folds  due  to 
unequal  contraction  of  the  paper  fibres.  The  better  way  is  to  sparingly  brush 
the  glue  on  the  reverse  side  of  the  drawing  only  at  the  comers.  Since  the 
tendency  of  most  workers  in  handling  glue  is  to  smear  it  in  many  places  aside 
from  where  it  is  needed,  and  because  of  the  manifest  difficulty  of  removing  a 
drawing  so  mounted,  which  occasionally  must  be  done,  the  use  of  the  glue  is 
not  warmly  advocated. 


MOUNTING.  25 

Sewing  is  a  clean  and  simple  way  of  mounting  a  drawing  and  in  many 
instances  quite  efficient.  It  presents,  nevertheless,  two  unpleasant  features: 
If  the  paper  is  much  handled,  in  which  sewn-on  drawings  are  contained,  the 
frequent  bending  of  the  pages  leads  to  a  sharp  strain  on  the  threads  causing 
them  to  tear  through.  This  is  particularly  common  if  the  drawings  are  mounted 
on  thin  paper.  Again,  the  removal  of  sewn-on  drawings  takes  time  and  some 
manipulation.  Fig.  15  gives  an  idea  how  to  place  the  stitches.  The  right 
hand  is  in  the  act  of  pushing  the  needle,  A,  armed  with  stout  thread,  through 
the  mount,  C,  and  the  drawing,  B.     When  this  has  been  done,  the  thread  is 


Fig.  16.- 


-Ulustrating  the  method  of  mounting  drawings  by  the  use  of 
slits  in  the  mounting  page. 


pulled  through  and  the  needle  carried  again  through  drawing  and  mount, 
forming  the  stitch  shown.  The  thread  is  then  securely  knotted  on  the  reverse 
side  of  the  mount.  At  i,  2  and  3,  the  stitches  already  placed  show  their 
diagonal  relation  to  the  corners  of  the  drawing. 

Fig.  16  gives  a  convenient  and  simpler  method  of  mounting  a  drawing. 
It  consists  of  slipping  the  corners  into  slits.  The  ease  and  neatness,  with  which 
this  can  be  done,  as  well  as  the  simplicity  of  removing  the  drawing  at  any 
time,  strongly  advocate  its  adoption.  Its  one  weak  point  is  that,  with  much 
handling,  one  or  more  corners  may  become  disengaged  and  the  drawing  fall 


26  LABORATORY    GUIDE    FOR    HISTOLOGY. 

from  the  mount.  This  can  be  avoided  largely  by  making  the  slits  at  such  a 
position  that  considerable  of  the  corners  will  slide  into  them.  At  i  and  2, 
the  corners  of  the  drawing,  A,  have  been  inserted  into  the  slits  through  the 
mounting  paper,  B,  while  at  3,  the  corner,  C,  is  drawn  back  to  a  point  where,  by 
letting  the  drawing  assume  its  natural  shape,  it  will  slip  easily  into  the  slit,  D. 

DRAWING  IN  COLOR. 

To  do  justice  to  the  use  of  colors  in  making  illustrations  of  microscopical 
subjects,  a  great  deal  more  space  would  be  necessary  than  is  here  available.  It 
is  well  realized  that  both  the  judgment  and  the  art  necessary  for  the  advantage- 
ous use  of  color  can  only  be  attained  by  considerable  training.  They  are  often 
apparently  inherent.  In  an  ordinary  class  of  students,  relatively  so  few  display 
any  true  skill  in  the  handling  of  colors  that  it  is  advisable  to  discourage  their 
general  use. 

However,  some  structures  are  classified  according  to  their  color-reaction 
when  treated  with  certain  stains;  consequently  drawings  of  them  must  be  made 
in  color.  .While  in  this,  as  in  all  things,  practice  will  do  so  much  for  even  the 
most  ungifted,  a  wise  rule  for  a  class  studying  microscopic  anatomy  is,  not  to 
attempt  the  use  of  colors  except  in  those  instances  in  which  color  differences  or 
color  differentiations  are  the  especial  and  distinctive  features  of  the  structures 
under  consideration.  For  example,  the  stain  or  color  reactions  of  the  cyto- 
plasmic granules  of  the  white  blood-corpuscles  are  distinctive  characters  of 
these  corpuscles  and  form  one  of  the  bases  upon  which  they  are  classified,  and 
therefore,  must  be  represented  in  colors;  or,  again,  the  color  differentiation  of 
the  neuroglia  is  the  chief  character  by  which  it  may  be  distinguished  from  the 
white  fibrous  tissue  with  which  it  is  mixed  in  the  central  nervous  system  and, 
in  drawings  involving  both  these  tissues,  the  use  of  color  is  quite  essential 
to  the  proper  imitation  of  the  features  by  which  they  are  recognized.  But 
in  all  ordinary  cases,  less  time  will  be  consumed  and  cleaner  and  more  concise 
results  will  be  obtained  with  drawings  in  black  and  white. 

In  the  use  of  colors,  the  general  student  must  choose  one  or  the  other  of 
the  two  simpler  methods  of  their  application,  namely,  the  superimposing  of 
crayons  or  of  water-colors  upon  the  outlines  and  certain  details  of  structure  al- 
ready drawn  in  with  pen  and  ink.  Of  the  two  methods,  the  use  of  crayons  is 
the  easier.  This  will  be  described  first,  followed  by  directions  for  the  use  of 
water-colors,  and  a  drawing,  given  in  steps,  which  will  serve  to  illustrate  both 
methods. 

Crayons. — ^First,  place  the  outlines  and  such  details  as  may  be  represented 
by  lines,  with  pen  and  ink,  then  give  the  required  color  to  the  different  struc- 
tures by  simply  rubbing  the  proper  crayons  over  them.  The  combination 
of  pen  and  ink  with  crayons  will  give  much  better  results  in  the  hands  of  most 
than  if  the  drawings  be  made  exclusively  with  crayons.  The  different  crayons 
have  already  been  discussed  sufficiently  in  the  description  of  materials.     When 


WATER    COLORS.  27 

filling  in  such  small  areas  as  nuclei,  the  crayon  should  have  a  sharp  point. 
Larger  surfaces,  however,  are  more  evenly  covered  when  the  point  is  blunt. 

One  principle  in  laying  in  the  different  tints  with  crayons  is  exactly  the 
same  as  that  described  in  the  paragraphs  on  black  and  white  drawing,  namely, 
always  work  from  light  to  dark  tones,  since,  in  the  use  of  crayons,  a  dark  tone, 
once  placed,  cannot  be  made  much  lighter  by  superimposing  a  lighter  color, 
and  it  is  likewise  impossible  to  erase  it  all  away.  But,  the  lightest  tint  in  colored 
drawings  cannot  always  be  carried  over  the  whole  drawing,  as  may  be  done 
in  the  use  of  black  pigment,  since  its  presence  may  often  render  the  correct 
coloring  of  certain  tissue  elements  an  impossibility.  For  example,  suppose  a 
portion  of  a  preparation  takes  a  purple  stain;  then,  an  underlying  tone  of 
yellow  would  entirely  preclude  the  placing  of  purple,  since,  as  already  shown, 
purple  contains  no  yellow  integer.  If,  however,  as  is  the  case  with  most  prepa- 
rations stained  with  hematoxylin  and  eosin  or  Van  Gieson,  the  lightest 
color  is  yellow  or  yellowish-red,  and  runs  all  through  the  different  tints  of  the 
preparation,  then  yellow  should  naturally  be  laid  in  one  mass  over  the  entire 
drawing.  It  would  be  least  evident  in  the  areas  occupied  by  nuclei,  for  example, 
but  could  be  found  in  all  the  elements  of  the  preparation,  and  must,  therefore, 
be  in  all  the  elements  of  the  completed  drawing,  modified,  of  course,  by  the 
superimposing  of  the  other  colors  required. 

To  obtain  differential  tints,  a  little  analysis  may  be  necessary.  For  example, 
suppose  certain  of  the  keratinous  structures,  as  in  sections  of  hairs  or  of  thick 
skin,  take  a  greenish  tinge;  then,  this  tinge  may  be  accomplished  by  super- 
imposing blue  upon  the  existing  yellow,  the  depth  of  the  green  depending  upon 
the  mixture  used.  Yellow-brown  tints  may  be  made  by  superimposing  Roman 
ocre  upon  the  yellow  ground  color.  The  tones  of  red,  blue  or  purple  of  the 
nuclei  may  be  attained  likewise  by  the  proper  mixing  in  the  proportions  found 
necessary. 

In  placing  the  dift'erential  colors,  it  will  be  found  that  the  superimposing 
of  colors  to  get  the  required  tints  frequently  gives  truer  and  more  pleasing 
results  than  are  to  be  obtained  by  the  use,  often  practiced,  of  a  single  crayon 
for  each  color.  This  is  so  chiefly  because  the  prepared  pigments  seldom 
truly  imitate  the  colors  of  the  stains  used. 

■  Two  important  precautions  are  to  be  observed  in  the  use  of  colored  crayons 
which,  as  described  under  materials,  consist  largely  of  wax;  namelv,  crayon 
should  not  be  blended  with  the  tortillion  and  should  never  be  fixed.  The  wax 
does  not  permit  of  blending  but  will  clump  under  the  pressure  and  rubbing, 
and  wax  is  soluble  in  the  fluid  portion,  the  alcohol,  of  the  fixing  solution,  a 
property  that  will  occasion  a  total  ruin  of  the  drawing  if  the  fixing  agent  is  used. 

Water  Colors. — The  various  articles  used  in  this  style  of  drawing  are 
described  in  the  discussion  of  materials.  Water  colors  may  be  applied  with 
a  brush  exactly  as  crayons,  that  is,  they  may  be  distributed  over  the  tissue 
details  which  have  previously  been  drawn  in  with  water-proof  ink.  Or,  again, 
water  colors  may  be  so  dispensed  with  both  brush  and  pen  that  the  resulting 


28  LABORATORY   GUIDE   FOR  HISTOLOGY. 

picture  more  closely  resembles  the  tissues  examined  than  one  made  by  any 
other  style  of  drawing.  An  example  of  this  method  of  applying  color  is  given 
in  Fig.  17.  This  drawing  was  executed  in  much  the  manner  as  that  practiced 
with  the  shades  of  black  in  Fig.  9,  and  the  steps  of  procedure  are  much  the 
same  as  required  in  the  use  of  crayons.  First  the  outline  and  linear  details  were 
placed,  then  the  ground  color;  following  that,  the  differential  colors,  and  lastly, 
the  finer  structural  details.  Portions  of  the  drawing  involving  these  different 
stages  are  inclosed  by  the  brackets  i,  2,  3,  and  4  respectively. 

The  stage  of  outline  here  is  in  all  respects  quite  the  same  as  that  described 
in  making  black  and  white  drawings.  The  ground  color,  however,  differs 
from  the  one  laid  in  Fig.  9,  in  the  fact  that  true  colors  were  used  instead  of 
some  degree  of  black.  As  previously  cautioned,  a  careful  inspection  of  the 
different  tints  in  the  preparation  must  be  made  before  attempting  to  lay  on  the 
ground  color.  This  inspection  of  the  preparation,  from  which  Fig.  17  was 
drawn,  gave  the  following  findings:  The  lightest  tint  was  presented  by  the 
tangentially  cut  hairs,  within  their  follicles,  a  pale  reddish  yellow  as  seen  at  a. 
The  next  lightest  tint,  a  much  diluted  red,  was  found  in  the  sebum,  h,  the 
partially  disintegrated  sebaceous  cells,  c,  and  in  the  sebaceous  cells  still  intact, 
d.  Following  this  light  red,  the  next  lightest  tint,  a  pale  purple,  could  be  seen 
underlying  the  nuclei  of  the  hair-sheath,  e,  and  the  sebaceous  duct,  /.  A  rather 
strong  yellow-red  came  next  in  order,  as  presented  by  the  connective  tissue  at  g. 
The  details  of  the  latter  and  the  outlines  of  the  sebaceous  cells,  h  and  i,  respec- 
tively, gave  the  next  darkest  tint  in  the  way  of  a  brick-red,  while  the  darkest 
color  of  all  could  be  seen  as  a  strong  purple  in  the  various  nuclei,  as  at  j. 

Accordingly,  the  three  primary  colors  were  found,  mixed,  it  is  true,  here  and 
there  to  give  some  of  the  secondary  colors.  As  was  stated  in  the  discussion 
on  the  use  of  crayons,  it  is  always  advisable  to  work  from  light  to  dark,  and 
this  principle  should  be  observed  in  the  use  of  water  colors.  Therefore,  the 
lightest  integers  in  the  different  tints  of  the  preparation  constitute  the  ground 
color,  and  may  be  seen  in  Fig.  17  as  yellow  in  the  connective  tissue  and  tangen- 
tially cut  hair,  k  and  /,  respectively,  and  as  red  in  the  hair-sheath,  m. 

The  stage  of  differential  color  has  been  left  unchanged  in  the  area  included 
by  bracket  3,  and  shows  how  the  color  of  the  connective  tissue  bundles,  g,  was 
accomplished  by  superimposing  red  on  the  existing  yellow,  and  how  the  delicate 
purple,  e,  underlying  the  nuclei  of  the  hair-sheath,  was  effected  by  washing 
blue  over  the  red  already  placed  in  the  ground  color. 

This  method  of  getting  desired  tints  by  superimposing  water  colors  will 
be  found  as  satisfactory  as  in  the  use  of  crayons,  and  for  the  very  same  reason 
given  under  that  head.  It  is,  however,  now  and  then  necessary,  and  quite 
often  practiced,  to  first  attain  the  desired  tints  by  bringing  the  colors  directly 
together  in  the  mixing-dish  and  subsequently  applying  them  with  the  brush 
to  the  drawing.  This  was  done  to  represent  the  body  color  of  the  nuclei  in 
Fig.  17.  Furthermore,  both  the  ground  and  differential  colors  should  be 
brushed  cm  in  excess,  and  then  this  surplus  color  is  to  be  removed  by  use  of  the 


'■''-U- 


-Hi 


WATER    COLORS.  29 

discharged  brush  as  described  in  the  use  of  black  pigment,  Fig.  11.  Accord- 
ingly, these  colors  should  be  prepared  somewhat  darker  than  the  tints  desired, 
since  all  of  the  pigment  will  not  remain  upon  the  drawing  when  the  excess  is 
removed. 

The  stage  of  detail  here  is  much  the  same  as  described  for  marking  drawings 
in  black  and  white,  save  that  the  real  colors  observed  in  the  tissues  are  used 
instead  of  black  or  some  degree  of  its  intensity. 

Occasionally  some  of  the  prepared  colored  drawing  inks  may  be  used,  and, 
where  this  is  possible,  Higgin's  will  be  found  the  best;  but,  the  fact  that  most 
of  these  inks  are  of  intense  brilHance  precludes  their  common  employment,  for 
results  thus  gained  often  resemble  some  style  of  Chinese  art  much  more  than 
examples  of  properly  stained  tissues.  Furthermore,  dilution  of  these  inks  does 
not  satisfactorily  soften  their  color  tones.  In  preparing  water-color  solutions 
for  the  placing  of  detail,  glue  or  gum-arabic,  should  be  incorporated  with 
them  by  using  the  method  given  under  dilution  of  black  pigment  and  for  the 
same  reason. 

Since  water  colors  do  not  rub,  there  is  no  need  of  fixing  them. 

It  should  be  mentioned,  in  closing  this  chapter,  that  any  conceivable  com- 
bination of  graphite,  ink,  crayon  and  water  color  may  be  utilized  to  illustrate  a 
microscopical  subject;  but,  since  only  individuals  of  skill  and  training  can  get 
anything  but  erroneous  and  unsightly  pictures  with  this  hybrid  method  of 
drawing,  the  beginner  is  strongly  advised  to  begin  and  complete  his  work  in 
one  style. 


SECTION  II. 

OUTLINES  FOR  LABORATORY  WORK. 

GENERAL   INSTRUCTIONS. 

Time  Required. — The  following  outlines  and  directions  for  laboratory- 
use  in  histology  and  microscopic  organology  cover  an  amount  of  work  which, 
in  the  experience  of  the  author,  may  be  accomplished  by  the  average  student, 
exercising  an  intelligent  economy  of  his  time,  in  a  course  allowing  three  labora- 
tory periods  of  three  hours  each  per  week  throughout  one  school  year.  The 
work  falls  under  three  general  heads,  each  requiring  approximately  the  same 
amount  of  time:  (i)  The  Histology;  (2)  Alicroscopic  Anatomy,  involving  the 
organs  comprising  all  the  functional  apparatuses  of  the  body  except  the  nervous, 
and  (3)  The  Central  Nervous  Apparatus,  or  system,  and  the  organs  of  special 
sense.  In  some  institutions  of  high  rank  it  is  not  thought  advisable  to  attempt 
to  cover  all  the  subjects  outlined  here  in  the  first  year,  the  time  being  so  allotted 
that  the  latter  part  of  the  work,  the  gross  and  microscopic  anatomy  of  the  central 
nervous  system  and  organs  of  special  sense,  is  offered  as  a  separate  course  in  the 
second  year.  There  are  good  reasons  for  this  arrangement,  based  upon  both 
curriculum  and  especially  upon  the  development  of  the  student's  information 
and,  in  such  cases,  that  part  of  these  outlines  dealing  with  the  nervous  organs 
may  be  used  as  a  guide  in  the  work  of  this  second  course.  In  institutions  not 
allowing  the  full  time  here  required  to  be  devoted  to  the  work,  portions  of  the 
outline  will  have  to  be  omitted  at  the  discretion  of  the  instructor. 

Nature  of  the  Work. — The  work  outlined  deals  wholly  with  normal 
tissues  and  organs.  In  certain  rare  cases  reference  is  made  to  abnormal 
structures,  but  this  is  done  solely  as  a  means  of  aiding  the  student  to  get  a 
more  concise  and  permanent  grasp  of  the  normal  appearances  and  normal 
microscopic  structure  and  relationships.  A  thorough  familiarity  with  the 
tissues  and  architecture  of  the  organs  of  the  normal  body  must,  of  necessity, 
precede  an  ability  to  study  intelligently  and  distinguish  pathological  modifi- 
cations and  a  comprehension  of  the  functional  and  structural  changes  produced 
by  disease. 

Preparations  of  human  tissues  are  frequently  called  for  in  the  directions  for 
the  study  of  the  different  subjects.  The  laboratory  in  which  these  outHnes 
have  been  used,  in  mimeographed  form,  during  the  past  years,  has  been  kindly 
given  access  to  autopsies  of  executed  criminals  from  time  to  time,  and  thus, 
fortunately,  has  been  able  to  supply  its  students  with  an  unusual  amount  of 
freshly  obtained  and  properly  fixed  human  material.  In  laboratories  in  which 
normal  human  material  is  not  available,  tissues  taken  from  the  monkey  and 

30 


NATURE    OF    THE    WORK.  3 1 

dog,  and,  at  times,  from  certain  others  of  the  domestic  animals,  will  serve  the 
purpose  more  or  less  satisfactorily,  for,  if  properly  chosen,  such  tissues  resemble 
the  human  quite  closely.  In  addition,  they  have  an  advantage  from  the  \'ie\v- 
point  of  comparative  anatomy.  Of  the  more  easily  available  domestic  animals, 
the  author  has  found  that  the  organs  of  the  dog  and  hog  are  more  generally 
identical  in  structure  with  the  human.  For  the  work  involving  the  histology 
proper,  the  tissues  of  any  of  the  higher  mamals  will  serve  in  most  all  cases. 
Hviman  blood,  for  example,  has  distinctive  features,  but  it  can  always  be 
obtained.  In  any  course,  the  cat,  rabbit,  rat,  and  at  times  the  frog,  are  called 
upon  as  a  matter  of  ease  and  convenience.  For  instance,  the  Pacinian,  or 
lamellated,  nerve-corpuscle  of  the  cat  is  practically  identical  in  structure  with 
that  of  man,  and  it  is  far  more  easily  obtained  and  better  preparations  can  be 
made  of  it  if  taken  from  the  mesentery  of  the  cat.  Furthermore,  in  the  organ- 
ology, while  the  chief  object  of  the  course  outhned  here  is  to  familiarize  the 
student  with  the  detailed  structure  of  the  human  body,  the  value  of  comparing 
the  organs  of  different  animals  with  those  of  man  is  recognized  as  exceedingly 
helpful  toward  that  object,  and  it  is  assumed,  even  when  human  material  is 
furnished,  that  the  student  will  frequently  be  given  preparations  from  similar 
organs  of  other  animals.  The  study  must  be  based,  of  course,  especially  by 
students  preparing  for  the  practice  of  medicine,  upon  the  structure  of  the  adult 
human  body,  whatever  the  variety  of  the  preparations  used. 

As  considered  advisable  in  a  course  of  this  kind,  the  classification  of 
structures  and  the  arrangement  of  topics  is  made  upon  an  almost  purely 
anatomical  and  functional  basis,  but,  every  care  should  be  taken  to  avoid  losing 
sight  of  the  embryological  principles  and  processes  giving  rise  to  the  structures. 
To  attain  an  intelligent  and  useful  familiarity  with  the  adult  structures,  a 
knowledge  of  the  origins  and  processes  by  which  the  various  tissues  and  organs 
are  developed  is  very  essential,  and  the  student  is  urged  to  keep  in  mind, 
in  every  case,  the  processes  by  which  arise  the  structures  embraced  under 
each  of  the  different  divisions  of  the  work.  At  times,  when  deemed  especially 
essential,  the  student  is  supplied  with  sections  of  embryos  and  preparations 
of  developing  tissues  and  organs  in  order  that  the  processes  of  their  origin  or 
elaboration  may  be  reviewed  or  studied  in  detail. 

One  of  the  most  common  defects  in  the  study  of  the  microscopic  structure 
of  the  tissues  and  organs  is  that  the  student  does  not  keep  in  mind  their  natural 
color,  physical  characters,  gross  appearances,  and  actual  relations  in  the  fresh 
condition.  The  mental  pictures  most  often  acquired  consist  wholly  of  the 
appearances  of  the  specially  treated  and  stained  preparations  of  the  structures 
with  no  suggestion  of  their  actual  appearance  in  the  body.  Furthermore,  a 
section  of  an  organ,  of  the  spinal  cord,  for  example,  may  be  studied  and  mastered 
as  to  its  detailed  structure  without  considering  its  position,  plane,  or  its  relations 
to  other  parts  of  the  organ,  that  is,  without  keeping  in  mind  the  shape,  extent 
and  relations  as  a  whole  of  the  organ  to  which  the  section  belongs.  For  pur- 
poses of  orientation,  and   in   order   that   this  very  usual   gap  between  gross 


32  LABORATORY    GUIDE    FOR    HISTOLOGY. 

and  microscopic  anatomy  may  be  bridged,  the  directions  here  given  begin 
with,  or  at  some  stage  involve,  the  consideration  of  the  macroscopic  appear- 
ances of  each  group  of  tissues  or  system  of  organs.  Somewhere  near  the 
beginning  of  the  study  of  each  subject,  or  group  of  allied  structures,  a  freshly 
killed  dog,  cat  or  rabbit,  or  material  from  the  butcher,  at  times  is  called  for 
for  this  purpose.  To  make  the  most  economical  use  of  this  material  when 
pro^•ided,  the  student  should  read  over  the  division  of  the  outlines  dealing 
with  the  given  group  of  structures,  note  the  parargaphs  in  which  the  study 
of  appearances  in  the  fresh  are  suggested  and,  in  their  sequence,  should  make 
all  such  studies  called  for  during  the  laboratory  period  in  which  the  fresh 
material  is  available.  The  transition  from  the  macroscopic  conditions  to  the 
microscopic  detail  is  made  with  the  hand  lens,  dissecting  microscope,  teasing 
methods,  free-hand  sections,  etc.  The  value  of  making  these  prelimin.-ry 
examinations,  whenever  possible,  can  hardly  be  too  strongly  emphasized. 

Again,  in  the  microscopical  study  of  a  preparation  of  a  tissue  or  organ,  one 
is  prone  to  omit  the  consideration  of  its  structural  and  architectural  resemblances 
and  its  relations  to  other  structures.  It  should  be  realized  that  there  are  no 
chasms  of  demarcation  between  structures,  no  abrupt  changes,  in  the  body. 
The  more  familiar  one  becomes  with  the  various  structures,  the  more  one 
realizes  that  there  may  be  found  gradual  transitions  between  the  varieties  of 
tissues  and  between  the  structures  of  organs.  The  sequence  in  which  the 
topics  of  the  different  subjects  are  arranged  is  usually  such  as  to  aid  in 
noting  resemblances  and  similarities  of  structure.  The  student  should  strive 
to  become,  finally,  so  familiar  with  the  organization  of  the  body  that  the 
structure  of  one  part,  called  to  mind,  will  suggest  that  of  another  and  so  on,  till 
the  entire  body  may  be  unwound,  as  it  were,  into  an  unbroken  chain. 

Let  all  studies  be  centered  upon  the  actual  tissues  themselves.  Use  the  text- 
books and  other  reading  matter  collaterally  as  a  means  of  becoming  able  to 
intelligently  observe  the  preparations.  Decide  upon  the  correct  answers  to 
the  questions  asked  throughout  the  outlines.  To  most  of  these  questions, 
direct  answers  are  expected;  some  are  asked  for  the  purpose  of  suggesting  obser- 
vations and  lines  of  inquiry  leading  to  further  conclusions. 

Preparation  of  the  Material. — The  more  detailed  study  is  made  from 
specimens  prepared  by  methods  of  technic  designed  to  emphasize  their 
principal  microscopic  features.  It  is  intended  that  the  routine  of  the  prepara- 
tions be  prepared  by  the  technical  assistant  of  the  department,  or  by  members 
of  the  teaching  staff,  and  issued  to  the  student  who  only  mounts  them  and 
labels  the  slides.  If  the  work  outlined  is  accomplished  in  the  time  specified, 
the  student  will  have  no  time  to  give  to  histological  technic  other  than  the 
amount  called  for  in  the  outlines.  Technic,  however,  is  a  very  necessary 
part  of  scientific  training  and  the  student  is  expected  to  be  more  or  less  familiar 
with  its  general  details  from  courses  taken  prerequisite  to  this  course.  If  not, 
he  should  take  a  special  course  in  histological  technic  rather  than  frequently 
interrupt  the  necessary  consecutiveness  of   the  study  of   the  subjects  of  this. 


LABELLING    AND    STORING    SLIDES.  T^T, 

another  course.  In  addition,  it  is  not  considered  advisable  for  the  students 
to  make  the  routine  preparations,  for  such  are  never  of  uniform  quaHty,  through- 
out the  class,  and  most  of  them  are  so  poor  and  unsuited  that  their  study 
largely  involves  an  unwarranted  waste  of  time.  However,  it  is  required  that 
each  member  of  the  class  be  familiar  with  the  general  methods  of  histological 
technic.  If  he  is  unable  to  present  proof  of  this,  he  is  required  to  present 
a  number  of  acceptable  preparations  made  in  his  extra  time  during  the  year. 
Their  preparation  must  include  the  process  of  removal,  fixation,  hardening, 
embedding  in  both  paraffin  and  celloidin,  sectioning,  and  staining  by  two  or 
three  of  the  common  methods. 

Except  where  especially  thin  sections  are  needed,  the  routine  preparations 
are  issued  to  the  class  in  the  form  of  celloidin  sections.  For  the  reception  of 
these,  each  student  is  supplied  with  a  stender-dish  with  ground-glass  cover.  Upon 
both  the  dish  and  the  cover  he  must  put  a  label  bearing  his  name.  An  amount 
of  ''clearing-oil"  is  kept  in  the  dish,  so  that,  in  issuing  the  sections,  the  assistant 
at  the  same  time  transfers  them  to  this  oil  where  they  are  cleared  ready  for 
mounting  by  the  student  with  the  least  possible  loss  of  time.  When  the  sections 
are  all  mounted,  the  dish  must  be  returned  to  the  assistant  to  receive  the 
succeeding  batch  of  sections.  Paraffin  sections  are  usually  mounted  on  cover- 
glasses  and  stained  and  cleared  by  the  assistant,  the  student,  in  these  cases, 
bringing  a  slide  with  a  drop  of  balsam  on  it  to  the  assistant  who  then  inverts 
the  cover-glass  upon  the  balsam.  The  assistant  will  strive,  in  supplying  the 
sections,  to  keep  well  ahead  of  the  class-w^ork  so  that  the  balsam  of  a  batch 
issued  will  have  time  to  harden  before  the  preparations  have  to  be  studied. 

The  dift'erent  methods  employed  in  making  the  preparations  called  for  in 
the  outlines,  are  summarized  in  Section  III.  For  the  detail  of  the  technic, 
the  student  is  referred  to  the  standard  text-books  of  histology,  special 
treatises  on  technic,  or  to  the  original  papers  describing  the  different  methods 
in  detail. 

Labelling  and  Storing  Slides. — Slides  of  perfect  white  glass  and  of 
medium  thickness  should  be  obtained.  The  thinnest  form  put  on  the 
market  is  too  apt  to  be  broken  in  routine  class-work,  and  the  thickest  involves 
an  amount  of  glass  unnecessarily  obstructing  the  light,- especially  should  it 
contain  flaws. 

The  standard  size  of  slide,  and  that  which  is  used  for  all  ordinarv  prepara- 
tions, has  a  measurement  of  75  x  25  millimeters  (3x1  inches). 

Choose  a  neat  square  label  of  pure  white  paper,  and  the  full  width  of  the 
slide.  There  are  many  slide  labels  on  the  market  which  do  not  possess  these 
qualities.  The  left  hand  end  of  the  slide  is  preferable  for  the  label  from  the 
fact  that  the  right  hand  is  usually  employed  with  the  focussing  of  the  micro- 
scope while  the  left  hand  is  used  in  moving  the  slide  on  the  stage,  and  the  eve 
falls  more  naturally  to  the  hand  holding  the  slide  when  it  is  necessarv  to  read 
the  label.  In  writing  the  labels,  exercise  uniformity.  The  following  formula 
will  sufiicc  for  most  specimens: 


34  LABORATORY    GUIDE    FOR    HISTOLOGY. 

(i)  The  subject  (name  of  tissue  or  organ). 

(2)  Source  (name  of  animal). 

(3)  Locality  (region  of  body  or  organ  from  which  preparation  is  taken). 

(4)  Plane  of  section,  if  important.  (If  not  a  section,  substitute  the  appro- 
priate word,  such  as  teased,  whole  mount,  smear,  etc.) 

(5)  The  method  of  preparation.  (If  a  special  method,  known  by  the  name 
of  its  deviser,  was  employed,  write  merely  the  proper  name,  such  as 
"Mallory,"  "Weigert,"  "Golgi."  If  a  common  method,  such  as 
celloidin  section,  stained  with  hematoxylin  and  eosin,  abbreviate,  as 
"Cel.  H   &  E.") 

Sometimes,  in  case  of  the  special  differential  methods,  it  is  well  to  write 
on  the  label  a  word  indicating  the  special  feature  shown  by  the  preparation. 
And  it  often  will  avoid  considerable  trouble  to  draw  a  ring  or  square  on  the 
cover  enclosing  the  area  of  the  preparation  showing  the  special  feature.  This 
ring  or  square  can  be  made  with  drawing  pen  and  water-proof  ink. 

For  storing  slides  for  use,  large  slide  boxes  are  always  preferable.  Of  these, 
the  cloth-covered  box  of  two  parts,  with  hinged  cover,  printed  index,  metal 
catch,  and  with  100  grooves  for  slides,  is  recommended.  With  medium  thin 
slides,  each  groove  of  this  box  is  capable  of  holding  two  slides  placed  back  to 
back.  The  cloth-covered  box  does  not  split  or  warp  as  does  the  wooden  one. 
The  small  wooden  boxes  occasion  more  delays  than  large  boxes  from  the  fact 
that  one  cannot  assemble  his  material  so  well  and,  when  it  is  necessary  to  refer 
to  a  certain  previously  used  preparation  during  the  study  of  another  subject, 
one  seldom  knows  in  just  what  box  it  is  stored.  As  to  the  system  to  be  used 
in  storing  the  slides,  it  is  suggested  that  they  be  grouped  and  arranged  in  the 
boxes  in  the  order  of  the  arrangement  of  the  subjects  and  topics  followed  in 
the  outlines.  Whatever  the  arrangement,  let  it  be  readily  usable  so  that  a 
given  preparation  may  be  found  with  the  least  possible  delay. 

Equipment  for  the  Work. — The  laboratory  is  supposed  to  furnish  each 
student  with  a  locker  and  key  and  a  set  of  apparatus  which  should  include  the 
following: 

I   Compound  microscope  and  case  with  several  oculars  and  objectives,  including  y.j 

oil-immersion. 
I  Dissecting  microscope. 
I   Balsam  bottle  containing  balsam. 
I  Wash-bottle  for  distilled  water. 
I  Tumbler. 

I   Bunsen  burner  wdth  rubber  gas-tube. 
I   Dissecting  pan  (broad  shallow  cake-pan). 
I   Petri  dish. 
I  Hand  towel  (exchanged  for  clean  one  when  soiled). 

1  Piece  of  small  glass  rod. 

2  Stender-dishes  (55  x  25  mm.),  with  ground  covers  to  match,  one  to  be  used  as  "section 

di.sh." 

3  Small  dropjjing  Ijottles. 
3  Test-tubes. 

6  Jars  for  staining  on  slide,  or  6  100  c.c,  salt-mouthed  pomade  or(|uinine  bottles  with 
corks. 


USE    OF    REAGENTS.  •  35 

2   100  c.c.  Reagent  bottles. 

6  50  c.c.  Reagent  bottles. 

2  8  c.c.  salt-mouthed  bottles,  with  corks,  one  to  be  used  for  glycerin. 

2  Sheets  of  filter-paper. 

3  Syracuse  watch-glasses. 

This  apparatus  is  to  be  returned  at  the  completion  of  the  course,  clean  and 
in  as  good  condition  as  when  received.  Reagents  may  be  obtained  at  need 
upon  requisition  from  the  store-room. 

In  addition  to  the  above  Hst,  the  student,  to  begin  with,  must  provide  for 
himself  the  following  equipment.  Other  articles  will  be  needed  during  the 
course,  but  these  may  be  obtained  as  occasion  arises. 

2  Sheets  of  Strathmore  bristol  board. 

3  Sheets  of  "Cap,  2-ply"  Reynolds  bristol  board. 
3  Drawing  pencils,  HE,  4H  and  5B. 

1  Large  soft  eraser. 

2  Drawdng  pen-points,  Gillott's  Lithographic,  No.  290,  and  Lithographic  Crow  Quill, 

No.  659. 

I  Pen  holder  to  suit. 

I  Ruler,  graded  in  millimeters. 

I  Bottle  waterproof  drawing  ink  (India  ink). 

6  Paper  "blenders." 

6  Thumb-tacks. 

8  Assorted  colored  crayons,  Faber's  preferred. 

I  Small  drawing-board,  12x8  inches. 

^  Gross  slides  (3x1  in.),  medium  thin. 

I  Oz.  Cover-glasses,  7-8  in.  square. 

I  Large  slide-box. 

I  package  of  slide  labels. 

I  Package  of  lens  paper. 

1  Small  camel's-hair  brush  for  manipulating  celloidin  sections. 

2  Medicine  droppers 

I  Section  lifter,  medium  size,  see  Fig.  18. 

I  Pair  cover-glass  forceps,  a  or  bj  Fig.  19. 

I  Pair  small  dissecting  forceps. 

I  Pair  small  dissecting  scissors.  Fig.  20. 

1  Scalpel,  medium  size,  for  dissecting  and  "scratch  erasures." 

2  Teasing  needles,  fine,  slender  points,  a  or  b,  Fig.  21. 
I  Section  razor. 

The  text-book  or  books  recommended  and  an  abundance   of  clean  soft  linen  or 
cotton  cloth  for  cleaning  cover-glasses,  slides,  etc. 

To  procure  other  than  sufficient  material  and  instruments,  and  those  of  the 
best  quality,  is  a  most  unprofitable  economy. 

It  is  advisable  to  cut  the  sheets  of  drawing  paper  into  four  equal  parts. 
They  can  be  more  conveniently  stored  and  easily  protected  from  soiling  in 
smaller  pieces,  than  in  the  original  boards.  At  need,  pieces  of  sizes  required 
may  be  taken  from  these  with  as  much  economy  as  from  the  larger  boards. 

The  teasing  needles  usually  on  sale  are  too  course  and  blunt  for  fine  teasing 
work.  The  student  can  make  a  better  article,  and  at  less  expense,  by  procuring 
a  paper  of  ordinary  sewing  needles,  No.  7,  Sharp's,  and  then  whittling  out 
handles  to  suit  of  soft  wood  into  which  the  needles  may  be  forced,  eye  first, 
with  a  pair  of  wire  forceps.     (See  Fig.  20,  a.) 

Use  of  Reagents. — Always  use  sufficient  of  a  reagent  but  not  a  wasteful 
amount,  and  use  a  given  reagent  only  for  the  purpose  for  which  it  is  intended. 


LABORATORY    GUIDE    FOR   HISTOLOGY. 


This  is  especially  applicable  to  the  staining  of  smear  preparations,  obtaining 
hematin  crystals,  etc.  When  discarding  them,  throw  all  solid  materials, 
acids,  stains,  etc.,  into  the  waste-jars  provided,  not  into  the  sinks.  Beware 
of  fluids  containing  acids  or  acid-salts  coming  in  contact  with  metal  pieces  of 
apparatus.     Not  only  will  the  apparatus  be  injured  but  the  composition  of 


Fig.  i8. 


Fig.  19. 


Fig.  20. 


Fig. 


Figs.  18  to  21. — Showing  styles  of  certain  of  the  instruments  referred 
to  in  accompanying  hst. 


the  fluid  will  be  changed,  j^robably  causing  failure  of  the  expected  results. 
Never  place  a  slide  giving  off  fumes  of  an  acid  on  the  stage  of  the  microscope. 
Care  and  Use  of  the  Microscope. — The  student  is  supposed  to  be  familiar 
with  the  general  construction  and  purpose  of  parts  of  the  microscope  from 
having  used  it  in  courses  previous  to  this.  Most  of  the  text-books  of  histology 
and  .some  of  the  treatises  on  histological  technic  give  detailed  descriptions 
of  the  construction  of  the  compound  microscofx'  anfl  the  physics  of  its  use, 
and  the  Spencer  Lens  Co.,  of  Buffalo,  N.  Y.,  publishes  a  j)amphlet  giving  its 


USE    OF    THE    MICROSCOPE.  37 

construction  and  precautions  for  its  use  which  is  supplied  for  the  asking.  It  is 
intended  here  only  to  call  attention  to  some  of  the  habits  formed  and  errors 
quite  commonly  committed  even  by  those  more  or  less  accustomed  to  the  use 
of  the  instrument. 

During  use,  it  is  quite  often  necessary  to  clean  the  lenses.  For  this  purpose, 
the  student  is  urgently  advised  to  keep  on  hand  a  supply  of  the  paper  made 
for  this  purpose  and  known  as  "lens-paper."  Use  a  small  piece  at  a  time,  and 
never  use  the  same  piece  on  two  occasions  for,  in  the  meantime,  it  may  have 
collected  dust  or  grit.  If  cloth  is  used,  let  it  be  of  soft,  perfectly  clean,  old 
linen,  cotton,  or  silk;  let  it  be  reserved  for  use  on  the  lenses  only;  let  it  be  kept 
in  a  place  protected  from  grit,  and  let  it  be  discarded  as  soon  as  it  is  soiled. 
It  is  a  common  habit  to  draw  the  handkerchief  from  the  pocket  and  apply  it  to 
a  lens.  Handkerchiefs  are  not  always  clean  nor  do  the  contents  of  the  pocket 
of  work  day  clothes  render  it  a  safe  place  for  a  lens  cleaner.  A  slight  scratch 
across  the  surface  of  a  lens  is  an  expensive  mishap,  and  continual,  though  very 
slight,  abrasions  by  dusty  cloths  will  eventually  render  it  necessary  to  send 
the  lenses  to  the  maker  for  repair.  The  ordinary  worker  frequently  gets  balsam 
on  the  objective.  This  may  be  removed  by  dipping  the  lens-paper  or  a  corner 
of  the  cloth  in  chloroform,  absolute  alcohol,  xylol,  or  any  ready  solvent  of 
balsam.  Chloroform  or  strong  alcohol  are  safer  from  the  fact  that  they  evapo- 
rate more  rapidly  and  consequently  less  time  is  allowed  for  them  to  attack  the 
substance  with  which  the  lens  is  cemented  in  its  position.  In  some  cases, 
balsam  itself  is  used  as  the  cementing  substance.  After  having  used  the  oil- 
immersion  lens  during  a  period  of  work,  always  clean  off  the  oil  before  putting 
the  microscope  away,  for  it  will  toughen  by  drying  before  the  next  period 
and  occasion  more  trouble  and  danger  in  its  removal.  Use  strong  alcohol 
with  the  lens-paper  for  this,  followed  by  dry  paper.  The  process  should  be 
repeated  with  clean  paper  to  remove  the  cloudy  film  of  water-vapor  and  oil 
usually  left  after  the  first  treatment.  Do  not  allow  the  alcohol  or  chloroform 
to  come  in  contact  with  other  parts  of  the  instrument.  The  lacquer  finish  may 
be  dissolved  and  the  metal  exposed  to  corrosion. 

Form  the  habit  of  being  careful  in  the  focussing  of  the  high  power  objectives 
lest  they  come  in  contact  with  the  slide.  Not  only  may  the  slide  be  broken, 
but  the  grinding  of  the  surface  of  the  lens  upon  it  is  far  more  to  be  deplored. 
A  good  plan  is  to  remove  the  eye  from  the  ocular,  and,  closely  observing  the 
objective,  run  it  down  till  it  almost  touches  the  slide,  then  return  the  eye  to  the 
ocular  and  focus  upward  till  the  field  comes  into  view. 

In  a  cool  room  especially,  the  close  proximity  of  the  nose  and  mouth  to 
the  barrel  of  the  microscope  results  in  a  condensation  of  the  vapor  of  the  breath 
upon  the  instrument,  often  so  great  that  it  runs  in  drops  upon  the  stage.  Not 
only  is  this  an  annoyance  to  the  worker,  but,  if  the  instrument  is  not  well 
lacquered,  it  is  conducive  to  corrosion  of  the  metal.  Its  continued  occurrence, 
leads  to  a  disintegration  of  the  lacquer  itself  followed  by  the  defacement  of  the 
metal  as  before.     This  condensation  of  the  breath  may  be  largely  avoided  by 


38  LABORATORY    GUIDE    FOR    HISTOLOGY. 

fitting  a  circle  of  good  quality  of  writing  paper  around  the  ocular.  The  circle 
may  be  about  two  inches  wide.  The  paper  quickly  acquires  the  temperature 
of  the  breath,  which  it  also  deflects  from  the  microscope,  and  therefore  conden- 
sation is  ob\'iated. 

Right-handed  individuals  should  form  the  habit  of  using  the  left  eye  at  the 
ocular,  so  that  the  right  eye  may  more  easily  be  transfered  to  the  drawing  on 
the  drawing-board  at  the  right.  Otherwise,  if  the  right  eye  is  used  for  the 
microscope,  the  head  must  be  lifted  and  the  nose  carried  across  the  ocular  in 
the  process  of  transferring  the  eye  to  the  drawing,  and,  in  doing  this,  the  nose 
or  cheek  often  comes  in  contact  with  the  ocular,  fogging  it.  Or,  if  the  ocular 
is  not  touched,  it  is  frequently  fogged  by  the  breath  in  the  passing  of  the  nose 
over  it.  Thus  the  lens-paper  or  cloth  must  be  frequently  produced  to  clean 
the  ocular  before  work  can  proceed.  The  use  of  the  left  eye  at  the  ocular  will, 
therefore,  not  only  save  considerable  time  in  the  course  of  the  day  and  consid- 
erable annoyance  in  changing  the  position  of  the  head,  but  will  greatly  decrease 
the  using  of  the  cleaning  cloth  upon  the  ocular  and  thus  decrease  the  possibili- 
ties of  injuring  the  lens. 

By  far,  the  greater  part  of  the  fatigue  experienced  in  laboratory  work  is  in- 
duced through  the  eyes.  With  some  workers  the  use  of  the  microscope  is  a 
continuous  strain  in  the  musculature  of  the  entire  optic  apparatus.  They 
squint.  Do  not  try  to  work  with  one  eye  closed,  but  form  the  habit  as  quickly 
as  possible  of  looking  into  the  miscroscope  squarely  with  both  eyes  open.  In  a 
very  few  sittings,  by  concentrating  the  attention  upon  the  object  in  the  instrument, 
one  can  learn  almost  unconsciously  to  neglect  the  image  formed  by  the  other  eye. 

Economy  of  Time. — The  author  knows  of  no  work  at  which  time  can  be 
more  abundantly,  frequently,  and,  often  unconsciously  wasted  than  in  the  histo- 
logical laboratory.  To  cover  the  work  outlined  here  in  the  period  allotted,  the 
student  must  consider  seriously  the  distribution  and  use  of  his  time.  He 
wastes  time  in  the  thoughtless  application  of  histological  technic,  in  the 
arrangement  of  his  material  and  apparatus,  in  a  lack  of  consecutive  thinking 
and  procedure,  but,  most  commonly  and  most  of  all,  does  he  waste  time  in  a 
lack  of  conciseness  of  purpose  in  going  about  his  work.  He  may  begin  work 
on  a  preparation  without  being  sufficiently  familiar  with  the  subject  to  dis- 
tinguish the  normal  from  the  abnormal,  artifacts  or  even  debris  from  actual 
structure;  he  will  begin  a  drawing  without  knowing  what  to  draw;  he  will 
uselessly  spend  a  lot  of  time  at  the  microscope  and  then  be  forced  to  consult  the 
text-book  before  he  can  proceed. 

First,  he  should  always  become  thoroughly  familiar  with  what  is  said  in  his 
text-books  and  lecture-notes  concerning  a  subject  before  taking  up,  in  the 
laboratory  hours,  the  preparations  illustrating  that  subject.  The  laboratory  is 
not  the  place  in  which  to  read  the  text-book,  especially  for  the  first  time. 

Second,  he  should  always  study  a  preparation  thoroughly  before  attempting 
to  draw  anything  from  it,  first,  under  low  power  for  orientation,  topography 
and  choice  of  a  suitable  field,  and  then  under  high  power  to  become  familiar 


DRAWINGS.  39 

with  the  more  detailed  structure.  He  should  decide  what  a  drawing  shall  be 
intended  to  represent  before  beginning  to  make  it.  Let  him  beware  of 
artifacts.     They  are  frequently  to  be  found  in  even  the  best  preparations. 

Third,  he  should  always  read  the  laboratory  outline  well  ahead,  and,  with 
his  preparations  before  him,  accordingly  plan  his  work  with  the  greatest  economy 
of  time. 

Drawings. — The  making  of  drawings  is  not  anatomy.  It  is  merely  a 
means  of  learning  anatomy.  Experience  has  shown  that  after  taking  the  pains 
to  carefully  portray  a  structure  on  paper,  that  structure  in  its  detail  is  more 
permanently  fixed  upon  the  mind  than  is  frequently  possible  by  any  other 
method.  It  is  not  necessary  to  draw  everything  studied;  only  the  more  important 
things.     One  should  study  far  more  than  he  draws. 

All  drawings  must  be  concise  in  character  and  neatly  done,  and,  above  all, 
they  must  accurately  portray  the  structures  under  consideration.  Drawings 
of  the  kind  that  may  be  popularly  called  "  Artistic  "  are  often  worthless.  Culti- 
vate a  sense  for  form  and  proportions.  Never  exaggerate  a  structure,  avoid 
"patching,"  and  beware  of  the  tendency,  toward  which  many  workers  are 
prone,  to  make  a  structure  appear  "  more  natural "  than  it  really  is.  In  drawing, 
one  learns  to  practice  habits  of  neatness  and  cleanliness  and  astuteness  of  obser- 
vation so  essential  for  everyone,  but  especially  for  the  successful  student  of 
medicine. 

Never  make  a  drawing  to  include  a  larger  area  of  the  preparation  than  is 
necessary  to  the  purpose  in  mind.  Drawings  involving  more  than  is  necessary, 
not  only  involve  a  waste  of  time,  but,  in  the  rush  of  laboratory  work,  are  often 
less  effective  and  generally  poor  in  desired  detail. 

For  line-drawings,  a  large  number  of  which  will  sufhce  in  an  ordinary 
course  in  microscopic  anatomy,  the  use  of  ink  is,  in  most  cases,  much  prefer- 
able to  pencil.  Lines  made  with  the  pen  are  not  only  more  precise  and  effec- 
tive, but  are  necessarily  more  thoughtful  from  the  fact  that  one  naturally  ponders 
longer  before  putting  the  pen  to  paper.  First  outline  in  light  pencil,  correcting 
as  to  scale,  curvatures,  number  of  lines  and  details,  and  then  complete  the 
drawing  in  ink  or  in  process  black  in  whatever  shades  desired.  Pure  line- 
drawings  are  usually  made  in  undiluted  black. 

Always  choose  carefully  the  field  from  which  a  drawing  is  to  be  made. 
Foreign  bodies,  grotesque  features  or  artifacts  produced  by  the  treatment  of  the 
specimen,  may  be  overlooked  till  after  the  drawing  is  well  underway  and  then  a 
new  field  may  have  to  be  chosen  or,  at  least,  the  drawing  may  have  to  be  dis- 
carded. Make  it  a  rule  to  study  a  preparation  thoroughly  before  attempting  to 
draw  anything.  Study  it  first  under  low  magnification  for  purposes  of  orienta- 
tion, and  for  areas  promising  a  field  suitable  for  illustration,  and  second,  under 
high  magnification  for  closer  examination  and  for  the  more  detailed  structure. 
Decide  what  is  normal  and  what  is  abnormal  in  the  preparation  and  what  the 
drawing  shall  be  intended  to  illustrate,  and  then  decide  upon  the  most  propi- 
tious magnification  under  which  the  drawing  may  be  made.     Then  the  colors 


40  LABORATORY    GUIDE    FOR    HISTOLOGY. 

represented  in  the  field  may  be  studied  and  analyzed,  or  their  color  values 
decided  upon. 

Finally,  let  it  be  noted,  that  with  most  student  workers  it  will  be  found  wiser 
to  confine  the  use  of  colors  to  those  drawings  only  in  which  it  is  necessary  to 
illustrate  color-differences;  to  the  portraying  of  those  structures  only  whose 
distinctive  characteristics  are  either  their  intrinsic  color  or  their  color  reactions; 
that  is,  their  special  differentiations  by  the  stains  employed  in  the  making 
of  the  preparations.  The  majority  of  preparations  are  stained  merely  to  facili- 
tate the  study  of  them  by  intensifying  structures  otherwise  seen  with  difficulty 
or  not  at  all.  Therefore,  in  the  maiority  of  cases,  the  color  imparted  by  the 
stains  need  not  necessarily  be  reproduced. 

For  aid  in  the  technic  of  drawing,  read  carefully  what  is  given  in  Section 
I.  While  the  treatment  there  is  by  no  means  exhaustive,  it  is  hoped  that  it 
may  be  of  use  in  the  saving  of  time  and  improvement  of  results. 

Collateral  Reading. — At  the  end  of  the  outline  for  each  general  subject 
there  is  given  a  list  of  the  original  papers  dealing  with  the  respective  structures 
considered.  These  are  merely  papers  chosen  from  among  the  far  greater 
number.  For  many  of  the  subjects,  the  literature  is  so  voluminous  that  in  the 
selection  of  the  advisably  few  for  these  lists,  numerous  papers  of  importance 
were  of  necessity  omitted.  Some  of  the  papers  cited  are  of  recent  date;  some 
are  old  but  all  are  the  better  for  it  in  that  they  have  stood  the  test  of  time. 
Monographs  and  dissertations  published  separately,  and  papers  occurring  in 
other  than  the  more  usually  available  journals  are  as  a  rule  avoided  in  these 
lists  as  probably  less  easily  obtainable  by  the  student,  and  papers  dealing  with 
mammalian,  and  especially  human  tissues  were  given  preference.  Students 
wishing  to  read  further  are  referred  to  the  literature  given  by  the  authors  of  these 
papers  and  to  the  current  numbers  of  the  journals  for  the  more  recent  literature. 
Many  of  the  publications  chosen  here  are  in  other  languages  than  English. 
The  best  advice  the  author  can  give,  is  read;  read  all  you  can  whenever  you 
can.     It  is  the  only  way  to  become  familiar  with  your  subject. 

The  Papers. — On  the  completion  of  the  study  of  each  of  the  general 
subjects  and  the  drawings  necessary  for  it,  the  student  is  required  to  incorporate 
his  results  in  a  paper  which  is  to  be  handed  in  to  the  instructor  for  examina- 
tion and  correction.  The  subjects  are  so  arranged  in  the  outlines  that  there 
will  be  twelve  of  these  papers  in  all.  Each  must  contain  an  epitome  of  the 
student's  laboratory  notes,  collateral  reading,  and  final  observations,  illustrated 
with  his  laboratory  drawings,  and  each  must  fully  cover  the  ground.  They 
are  not  only  required  for  the  formation  of  the  instructor  as  to  the  progress 
of  the  student,  but  chiefly  on  account  of  their  pedagogical  value  to  the 
student  himself. 

As  is  well  known,  the  writing  down  of  one's  impressions  is  the  most  excellent 
means  of  fixing  them  in  the  mind,  but,  in  addition,  in  papers,  the  student  has 
that  opportunity  to  assemble  his  information,  to  systematize  and  to  summarize 
it,  so  necessary  for  the  acquiring  of  a  well-rounded,  definite  grasp  of  a  subject. 


THE    PAPERS. 


41 


In  the  arrangement  of  the  material  and  the  writing  up  of  a  subject,  one  will 
often  be  impressed  with  resemblances  and  relationships  of  structures  not  seen 
before,  but  the  realization  of  which  aids  greatly  in  making  his  knowledge  of  the 
subject  consecutive. 

In  the  construction  of  the  papers,  it  is  suggested  that  the  topics  involved  be 
arranged  in  the  order  followed  in  the  outline  for  the  given  subject  and  that  the 
laboratory  drawings  be  arranged  accordingly  in  their  natural  sequence.  Make 
abundant  use  of  the  drawings  to  illustrate  the  text  descriptions,  referring  to 
special  features  by  means  of  the  letters  or  the  names  indicating  them  in  the 
drawings.     Let  the  text  be  as  brief  as  possible,  making  each  paper  little  more 


Fig.  22. — Showing  the  furm  of  paper  and  paper-fasteners,  and  suggesting  a  method  of 
arranging  the  drawings  and  text  for  laboratory  papers. 


than  a  summary  of  a  systematized  presentation  of  the  detailed  characters, 
relationships,  and  functional  significance  of  the  structures,  and  the  general 
conclusions  of  the  worker  reached  from  his  laboratory  observations  and 
corrected  from  his  lecture  notes,  texts,  and  collateral  reading. 

While  the  work  of  constructing  these  papers  must  be  done  outside  of  labor- 
atory hours  and  is  tedious  and  time-consuming,  at  the  end  of  the  course  the 
student  will  have  his  year's  work  so  collected  and  arranged  that  in  other 
courses  he  will  refer  to  it  at  need  in  preference  to  his  text-book  and  with  better 
results,  for  the  pages  will  bring  back  to  him  the  actual  appearances  and  studies 
of  the  preparations  themselves.  In  actual  experiences  of  a  number  of  years, 
so   universal    has   been   the   satisfaction   of    having  done    the    work,  that    the 


42  LABORATORY    GUIDE    FOR    HISTOLOGY. 

author  remembers  no  case  in  which  a  student,  at  the  end,  has  regretted  the 
time  and  labor  spent. 

The  writing-paper  used  for  the  laboratory  papers  should  be  of  uniform  size 
and  quality  throughout  the  course.  Ordinary  letter-size  (ii  X  ^i  inches),  in 
separate  sheets,  unruled,  is  recommended.  It  should  be  obtained  with  two 
perforations  at  the  side,  as  shown  in  Fig.  22,  in  order  that  the  pages  of  each 
paper  may  be  tied  or  clasped  together.  No.  24,  "paper  fasteners,"  such  as 
shown  in  Fig.  22,  will  be  found  very  satisfactory. 

It  is  more  satisfactory,  both  in  construction  and  to  the  reader,  that  one  side 
of  the  page  only  be  written  upon.  Always  leave  a  left-hand  margin  of  fair  size 
for  convenience  of  the  reader  in  indicating  corrections  and.  for  the  occasional 
necessity  on  the  part  of  the  writer  of  inserting  notes  of  points  omitted.  In  this 
margin  also  may  be  written  the  topic  headings  so  that  they  may  be  readily 
found  both  by  the  reader,  and,  at  need,  by  the  writer  (see  Fig.  22). 

Always  mount  the  drawings  on  the  side  of  the  page  facing  the  text  and  as 
near  as  convenient  to  the  part  of  the  text  describing  them  (see  Fig.  22).  Let 
the  drawings  be  referred  to  as  figures  and  numbered  consecutively  throughout 
a  paper.  When  several  drawings  are  mounted  on  the  same  page,  that  page 
should  be  referred  to  as  a  plate  and  the  plates  should  be  numbered  consecu- 
tively throughout  the  course.  Number  the  plates  in  Roman  characters  and  the 
figures  in  Arabics.  Then,  having  the  drawings  lettered  (or  the  names  of  the 
structures  attached)  and  the  figures  and  plates  numbered,  at  any  place  in  a 
paper,  one  may  refer  to  a  certain  detail  shown  in  any  drawing  by  citing  the 
plate,  the  figure  and  the  reference  letter  as,  for  example,  "Plate  IV,  Fig.  2,  a." 

The  use  of  diagrams,  schematic  drawings  and  reconstructions  are  frequently 
of  great  convenience  and  time  saving  value  in  describing  structures  and  the 
interrelationship  of  the  parts  of  an  organ  or  apparatus,  and  is  strongly  advised. 
If  the  diagrams  required  are  small,  they  may  be  drawn  in  the  text-page  as 
needed.  If  large  and  more  formal  diagrams  are  required,  drawing  paper  should 
be  used  and  they  should  be  labeled  and  mounted  and  numbered  as  ordinary 
figures. 

When  the  paper  is  assembled,  put  on  a  blank  page  at  either  side  for  protec- 
tion, and  write  across  the  front  one  of  these  pages  the  number  of  the  paper  and 
its  general  title  in  large  characters,  thus: 

"PAPER  VI. 

THE  RESPIRATORY  APPARATUS." 

Then  put  the  name  of  the  writer  and  the  date,  in  ordinary  script,  at  the 
lower  right  hand  corner  and  the  paper  is  ready  to  be  handed  in. 


THE  OUTLINES. 

(first   paper.) 

I.  INTRODUCTORY  EXERCISES. 

Fabric  Fibers.  -Cotton  libers,  strands  of  wool  from  the  clothing,  shreds 
of  linen,  and  hain  sometimes  get  caught  upon  the  laboratory  preparations. 
That  the  student  may  be  able  to  recognize  these  when  they  are  found,  also  as 
a  preHminary  test  of  his  powers  of  observation  and  abihty  to  use  the  microscope 
the  following  exercises  are  given: 

1.  Mount  in  water  on  the  same  slide,  a  human  hair,  a  few  white  rabbit 
hairs  and  a  strand  of  wool.  Examine  first  under  low  power  and  then  under 
high.     In  what  features  do  they  differ? 

2.  On  separate  slides  mount  in  the  same  way  a  few  cotton  fibers,  some 
finely  separated  threads  of  linen  and  some  strands  of  silk.  Examine  them  under 
high  power.  In  what  features  does  the  cotton  differ  from  the  wool  and  silk? 
What  is  the  origin,  nature  and  structure  of  each? 

3.  On  the  same  piece  of  drawing  paper,  make  drawings  of  short  segments 
of  all  six  specimens.  Compare  them  carefully  and  enumerate  the  distinctive 
features  of  each. 

II.  THE  CELL. 

1.  Vegetable. 

(a)  Clip  out  a  small  square  from  one  of  the  thin  membranes  between  the 
leaves  of  an  onion,  and  also,  with  razor,  make  a  thin  longitudinal 
section  of  a  bit  of  the  thicker  onion  leaf.  Mount  both  specimens 
in  water  and  examine.  What  is  the  shape  of  the  cell  in  both  prepara- 
tions, and  where  are  the  nuclei  situated?  Crystals  in  cytoplasm? 
Draw  one  cell  from  each  showing  contents  of  cells  and  their  position 
with  reference  to  other  cells.  Functions  of  the  cells  as  suggested 
by  their  contents? 

(b)  On  the  same  slide,  mount  in  water  a  small  piece  of  the  skin  of  a 
potato  and  also  a  thin  section  of  the  potato.  Examine  under  both 
low  and  high  power.  In  what  do  the  cells  from  the  two  regions 
dift'er  as  to  cell  contents?  Sketch  a  cell  from  each  region,  showing 
shape,  relative  size,  and  cell  contents.  Difference  between  cell- 
membrane  and  cell-wall  ?  Under  high  power  sketch  a  large  starch- 
grain.     Explain    its    appearance    and    formation. 

2.  AnimaL 

(a)  Epidermal  scales,  etc.  Mount  a  drop  of  saliva.  Also  on  another 
slide  mount  in  70  percent,  alcohol,  some  scrapings  from  the  cheek. 

43 


44  LABORATORY    GUIDE    FOR    HISTOLOGY. 

What  varieties  of  cells  are  to  be  observed?  Are  any  of  them 
living?  Other  structures  than  cells?  What  are  the  "salivary 
corpuscles?" 

(b)  The  living  cell.  Mount  a  small  drop  of  hay  infusion  (furnished). 
Watch  an  ameba  and  sketch  it  at  three  or  four  different  intervals. 
How  do  cytoplasm  and  nucleus  behave  ?  How  does  the  cell  (animal) 
move  ?  Exoplasm  and  endoplasm  ?  Explain  the  method  of  move- 
ments of  the  free-swimming  organisms  in  the  mount.  Note  particles 
(organic  and  inorganic)  exhibiting  "Brownian  movement"  and 
explain  it. 

(c)  Examine  under  high  power  stained  preparations  of  amebae.  How 
do  the  nucleus  and  cell  contents  differ  from  those  of  the  living  cell  ? 

(d)  Animal  ova — stained. 

(i)  Sketch  a  few  echinoderm  or  fish  ova  in  the  early  stages  of 
division,  the  2-cell,  4-cell,  and  8-cell  stages. 

(2)  From  sections,  sketch  an  ovum  in  the  blastula  stage.  Do  the 
cells  in  (i)  and  (2)  differ  in  size?  What  is  the  gastrula  and 
how  is  it  derived?    Are  th^re  karyokinetic  figures  observable? 

3.  Cell  Division. — The  process. 

(a)  From  stained  sections  (furnished)  of  animal  ova  or  of  other  suitable 
tissue,  draw  cells  showing  the  following  phases  of  karyokinesis: 

(i)  Resting  stage  of  nucleus. 

(2)  Chromatin  filaments  in  "close  skein." 

(3)  Loose  skein. 

(4)  "Mother  aster"  and  centrosome.with  polar  radiation. 

(5)  "Daughter  asters"  and  spindle.  Explain  the  appearance  of 
the  equatorial  zone. 

(6)  Sketch  a  cell  showing  the  division  of  the  cytoplasm. 

After  the  division  is  completed,  what  is  the  condition  of  the  nucleus?  What 
changes  constitute  the  prophase,  metaphase  anaphase,  and  telophase  respec- 
tively?    Name  the  six  drawings  according  to  the  phases  represented. 

(b)  Draw  three  or  four  stages  of  dividing  nuclei  ("  germinal  cells") 
from  sections  of  the  neural  tube  of  a  mamalian  embryo.  Is  there 
a  cell  membrane?     Evidences  of  a  syncytium? 

(c)  Make  one  or  two  drawings  of  the  nuclear  structures  alone  from 
stained  sections  of  the  growing  root-tips  of  tradescantia  or  of  the 
onion,  showing  in  greater  detail  the  behavior  of  the  chromosomes 
(larger  here  than  in  the  animal  cell). 

Discuss  heterotypic  mitosis  as  differing  from  homotypic  mitosis.  Give 
reasons  for  the  assumption  that  mitosis  and  amitosis  are  but  the  two  ex- 
tremes in  form  of  a  process,  between  which  extreme  all  gradation  forms  exist. 


EMBRYOLOGICAL    DEVELOPMENT.  45 

Give  the  two  most  probable  theories  of  the  origin  of   the  Centrosome.     What 
is  indicated  by  the  presence  of  more  than  two  centrosomes  (pluripolar  metosis)  ? 

III.  EMBRYOLOGICAL  DEVELOPMENT 

I.  Sketch  a  transverse  section  of  a  vertebrate  embryo,  showing  an  early 
stage  in  the  formation  of  the  three  germ  layers.  Designate  the  chorda,  neural 
tube,  anlagen  of  spinal  ganglia,  etc.  What  is  the  origin  of  the  mesoderm? 
Carefully  fix  in  mind  which  tissues  of  the  body  are  derived  from  each  of  the 
germ  layers. 

LITERATURE  ON  THE  CELL. 

General  Anatomy. 

AWERINZEO,  S.  Beitrage  zur  Struktur  des  Protoplasmas  und  des  Kernes  von  Amoeba 

protens.     Zool.  Anz.,  Bd.  32,  No.  2,  p.  45,  1907. 
BERGEN,  F.  Zur  Kenntnis  gewisser  Strukturbilder  (Netzapparate,  Saftkanalchen  Tropho- 

spongien)    im   Protoplasma    verschiedener    Zellenarten.     Arch,   fiir    Mik.    Anat., 

Bd.  64,  H.  3,  p.  498,  1904. 
F.AURE,  E.  Sur  la  structure  du  protoplasma  chez  les  infusoires  cilies.     Compt.  rend.  Soc. 

Biol.,  T.  57,  No.  26,  p.  123,  1904. 
GOETT,   T.    Die    Speichelkorperchen.    Internat.    Monatsschr.    f.    Anat.    u.    Physiol.    Bd. 

23,  H.  10,  p.  378,  1906. 
HEIDENHEIN,    M.  Weitere    Beitrage    zur    Beleuchtung    des    genetischen    Verhaltnisses 

zwischen  molecularer  und  histologischer  Struktur.     Anat.  Anz.,  Bd.  21,  p.  391,  1902. 
JOSEPH,   H.  Zur  Beurteilung  gewisser  granularer  Einschllisse  des  Protoplasmas.     Anat. 

Anz.,  Bd.  25,  p.  105,  1904. 
KUNSTLER,  G.  La  nomenclature  des  elements  protoplasmiques.     Compt.  Rend.  Soc.  Biol., 

April,  1906. 
LEDUC,  S.  Croissance  de  la  Cellule  artificielle.     Compt.  rend.  Assoc,  franc,  pour  I'Avance 

d.  Sc,  p.  601,  1906. 
LEVI,  G.  Vergleichende  Untersuchungen  liber  die  Grosse  des  Zellen.     .\nat.  Anz.,  Bd.  27 

p.  156,  1905. 
REINKE,  F.  Ueber  die  Beziehungen  der  Wanderzellen  zu  den  Zellbriicken,  Zelliicken  und 

Trophospongien.     Anat.  Anz.,  Bd.  28,  No.  15-16.  1906. 
ROHDE,  E.  Untersuchungen  liber  den  Bau  der  Zelle.  IV.  Zum  histologischen.  Wert  der 

Zelle.     Zeitschr,  f.  wiss.  Zool,  Bd.  78,  H.  i,  p.  i,  1904. 
SCHUBERG,  A.  Ueber  Zellverbindungen.     Verhandl.  Anat.  Gesellsch.  \'ers.  21.  Wlirzburg, 

p.  56,  1907. 
SIEDLECKI,   M.  Ueber  die   Bedeutung  des   Karvosoms.     Anz.   der  .\kad.   der  Krakan. 

Math. — Nat.  Klasse,  1905. 
SKROBANSKY,   K.  Zur  Frage    den    sogenannten   "Dotterkern"    (Corpus  Balbiani)   bei 

Wirbeltieren.     Arch,  flir  Mik.  Anat.,  Bd.  62,  p.  194,  1903. 
WALLENGREN.  Zur  Kenntnis  der  FHmmerzellen.     Zeitschr  flir  allg.   Physiol.  Bd.  5,  H. 

4,  1905- 

Cell  Division. 

BAUMG.ARTNER,  W.  J.  Some  New  Evidences  for  the  Individuality  of  the  Chromosomes. 

Biol.  Bull,  of  the  Marine  Biol.  Laborat.  Woods  Hole,  Mass.,  Vol.  8,  No.  i,  1904. 
BOVERI,  T.  Ueber  das  Yerhalten  des  Protoplasmas  bei  monocentrischen  Mitosen.     Sitz- 

ungsber.  d.  phys.-med.  Ges.  Wiirzburg,  No.  i,  p.  12,  1903. 
CHILD,  C.  M.  On  the  Relation  between  Mitosis  and  Amitosis.     Biol.  Bull.,  Vols.  12  and  13, 

1907. 
CONKLIN,  E.  G.  E.xperiments  on  the  Origin  of  the  Cleavage  Centrosomes.     Biol.  Bui., 

Vol.  7,  p.  221,  1904. 
EYCLESHYMER,  A.  C.  The  Development  of  Chromatophores  in  Necturus.     Amer.  Jour. 

of  Anatomv,  Vol.  V.,  No.  3,  p.  309,  1906. 
FARMER,  J.  B.,  and  SHORE,  D.  On  the  Structure  and  Development  of  the  Somatic  and 

Heterotvpe  Chromosomes  of  Tradiscantia  \"irginica.     Quart.  Journ.  of  ^Mikrosc. 

Sc,  N.'S.  No.  192  (Vol.  48.  Pt.  4),  P-  559>  1905- 


46  LABORATORY    GUIDE    FOR    HISTOLOGY. 

HARTOG,  M.  The  Dual  Force  of  the  Dividing  Cell.     Pt.  i:  The  Achromatic  Spindle  figure 
Illustrated  by  Magnetic  Chains  of  Force.     Proc.  Royal  Soc,  Series  B,  Vol.  76  (Nov. 

9).  1905- 
HARTOG,  M.  The  Strain-figures  of  "Like"  Poles,  and  Rhumbler's  "Gummiring  Modell" 

in  Relation  to  the  Cytoplasmic  Spindle.     Arch.  f.  Entwicklungsmech.  d.  Org.,  Bd. 

19,  H.  I,  p.  79,  1905. 
VON  KORFF,  K.  Weitere  Beobachtungen  liber  das  Vorkommen  V-formiger  Centralkorper. 

Anat.  Anz.,  Bd.  19,  p.  490,  1901. 
LAWSON,  A.  A.  The  Gametophytes,  Archegonia,  Fertilization,  and  Embryo  of  Sequoia 

sempervirens.     Annals  of  Botany,  Vol.  18,  No.  69,  1904. 
MALTAUS,  M.,  and  MASSART,  J.  Sur  les  excitantes  de  la  division  cellulaire.    Rec.  de  I'inst. 

bot.  Les  Errera.  Bruxelles.  T.  6,  p.  369,  1907. 
MEMILOFF,  A.  Zur  Frage  der  amitotischen  Kernteilung  bei  Wirbeltieren.     Anat.  Anz., 

Bd.  23,  p.  353,  1903. 
MRAZEK,  A.,  and  VEJDOVSKY,  F.  Umbildung  des  Cytoplasma  wahrend  der  Befrucht- 

ung  und  Zellteilung.     Archiv  fiir  Mik.  Anat.  Band  62,  1903  . 
NUSSBAUM,  M.  Ueber  Kern- und  Zelltheilung.  Arch.  f.  Mik.  Anat.,  Bd.  59,  H.  4,  1902. 
REINKE,  F.  Zellstudien.     II.  Theil,  Arch,  fur  Mik.  Anat.,  Bd.  54,  p.  259,  1895. 
SCHLAEPFER,  V.  Fine  physikahsche  Erklarung  der  achromatischen  Spindelfigur  und  der 

Wanderung  der  Chromatinschleifen  bei  der  indirekten  Zellteilung.     Arch.  f.  Ent- 
wicklungsmech. d.  Organ.,  Bd.  19,  H.  i,  p.  108,  1905. 
TELLYESNICZKY,  K.  Ruhekern  und  Mitose.     Arch,  fiir  M"^ik.  Anat.,  Bd.  66,  p.  367,  1905. 
WATASE,  S.  Microsomes  and  Their  Relations  to  the  Centrosome.  Science,  Vol.  V.,  No.  no 

1897. 


THE  TISSUES. 

I.  EPITHELIUM. 

(second  paper.) 
A.  The  simple  Epithelia  (with  or  without  cilia). 

1.  Simple  squamous. 

(a)  Stretch  a  small  area  of  fresh  mesentery  with  interfitting  hard  rubber 
rings  or  over  a  piece  of  cork  or  glass,  and  treat  with  i  per  cent, 
silver  nitrate  i  to  12  hours,  keeping  in  the  dark.  Replace  silver 
nitrate  with  glycerin,  mount  a  small  piece,  spread  fiat  in  glycerin 
on  a  slide,  and  expose  to  diffuse  sunlight  till  silver  is  sufl&ciently 
reduced  to  show  the  cell  boundaries.  Draw  a  small  area  of  the 
epithelium  (mesothelium)  showing  the  shape  and  arrangement 
of  the  cells.  How  would  they  appear  in  vertical  section?  Ex- 
plain the  appearance  of  the  cell  boundaries.  Look  for  stygmata. 
HoW'  different  from  stomata  ?  Likewise  draw  an  area  of  the  inner 
lining  (intima)  of  a  capillary  contained  in  the  preparation.  In 
what  does  this  "endothelium"  differ  from  the  "mesothelium"? 
From  what  germ  layer  are  both  derived? 

(b)  Pigmented  simple  squamous.  Remove  a  bit  of  the  pigmented 
stratum  of  the  retina  from  an  eye  (white  rabbit  preferable)  that 
has  been  preserved  in  formalin.  Place  in  95  per  cent,  alcohol, 
10  minutes;  transfer  to  clearing  oil,  15  minutes;  spread  fiat  on  the 
slide,  remove  oil  with  filter  paper  and  mount  in  balsam.  Sketch 
a  few  adjacent  cells  showing  their  shape  and  characters. 
Position  of  nuclei?  Explanation  of  minute  round  areas  void  of 
pigment  granules  ?  Where  in  the  body  may  be  found  other  pigment- 
bearing  epithelia  ? 

2.  Cubic  epithelium. 

(a)  From  a  stained  section  of  kidney,  liver,  or  salivary  gland,  draw  a 
portion  of  a  duct  showing  the  characters  of  this  type. 

(b)  Ciliated  cubic.  Make  an  illustration  of  this  type  of  epithelium 
from  a  stained  section  of  a  lung.     In  what  passage  is  it  found? 

3.  Simple  columnar  epithelium. 

(a)  Non-ciliated. 

(i)  Cut  a  small  piece  from  the  pyloric  end  of  a  fresh  mammalian 
stomach  and  place  in  a  dissociating  fluid  (Ranvier's  one-third 
alcohol,  for  example)  and  let  it  remain  one  to  four  days.     Gently 

47 


48  LABORATORY    GUIDE    FOR    HISTOLOGY. 

transfer  a  bit  of  the  epithelial  lining  to  a  slide,  carefully  tease 
with  needles,  mount  in  water  and  gently  tap  the  cover-glass  for 
further  dissociation.     Examine  for  isolated  cells.     Add  at  the 
edge  of  the  cover  a  few  drops  of  an  aqueous  solution  of  alum  car- 
mine or  very  dilute  Congo  red.     When  the  cells  and  their  nuclei 
are  differentiated,  replace-  the  stain  with  glycerin  and   again  tap 
the   cover-glass.      {Note. — To   replace    a  fluid    under   a   cover- 
glass,  place  a  drop  of  the  required  fluid  at  one  edge  of  the  cover 
and  a  bit  of  filter  paper  at  the  opposite  edge  and  so  manipulate 
that  the  required  fluid  is  gently  drawn  under  the  cover.)    Sketch 
a  few  isolated  cells  and  also  a  small  row  still  associated.     Gen- 
eral shape  of  the  cells  ?     Where  is  the  nucleus  situated  ? 
(2)  From  one  of  the  villi  in  a  thin  stained  section  of  the  small  intestine 
make   a   drawing  illustrating   the   arrangement,    character   and 
structure  of  its  epithelium.     How  does  it  differ  from  that  of  the 
stomach?^     Position,  nature,  and  significance  of  the  striated  or 
cuticular  border?     Include  a  "goblet  cell."      What  is  its  struc- 
ture, function,  and  origin  ?     Position,  function  structure,  and  ori- 
gin of  the  basement  membrane? 
(b)   Ciliated  simple  columnar  epithelium.     Sketch  showing  an  exam- 
ple of  this  type  either  from  a  stained  section  of  a  Fallopian  tube, 
of   lung,   or   of   certain    of  the  seminal  ducts.      What  are  ciUa? 
Their    relation    in    the    anatomy    of    the    cell?      Mention    three 
theories  advanced  to  explain  ciliary  action. 

4.  Pseudostratified    epithelium  (usually    ciliated). 

This  type  is  a  transition  form  between  simple  and  stratified  col- 
umnar epithelium  and  may  be  found  in  any  system  of  passages 
containing  these  two  types.  Sketch  an  example  from  a  stained 
section  of  the  epididymis  or  from  a  section  of  the  lung.  What 
produces  the  appearance  meriting  the  name? 

B.  The  Stratified  Epithelia  (with  or  without  cilia). 
I.  Stratified  squamous. 

(a)  Pare  off  a  small  plate  of  the  outer  layer  of  the  epidermis  (stratum 
tum  corneum)  from  the  palm  of  the  hand  and,  holding  it  in  pith, 
cut  with  razor  thin  vertical  sections  and  mount  them  in  water. 
How  are  the  scale-like  "cells"  arranged  with  reference  to  each 
other  and  with  reference  to  the  surface  of  the  body?  Their 
structure?  Sketch  a  small  group.  Replace  water  with  15  per 
cent,  potassium  hydrate  and  examine  again.  What  action  is  pro- 
duced by  the  KOH?     Nuclei?     Sketch  a  few  cells  as  modified. 

(b)  Make  a  careful  drawing  of  a  stained  vertical  section  of  human  skin 
from  the  volar  surface  of  the  finger  showing  in  detail  the  different 


GLANDULAR    EPITHELIUM.  "  49 

strata  composing  the  epidermis  and  the  characteristics  of  the  cells 
forming  each.  "Prickle  cells"  and  "intercellular  bridges"? 
Enumerate  the  changes  giving  rise  to  the  stratum  corneum.  In- 
clude the  cerium  in  the  drawing.  Nature  of  its  two  layers  ?  Ter- 
minal nerve  corpuscles  in  papillae  corii  ?  Other  corpuscles  found 
in  the  tela  subcutanea?  What  is  the  form  of  nerve  endings  in  the 
epithelium  proper  ?  Is  aquamous  epithelium  ever  ciliated  ?  Types 
of  glands  in  the  section  and  their  origin  ? 
(c)  Compare  section  (b)  with  a  similar  section  of  skin  taken  from  the 
general  surface  of  the  body,  and  enumerate  the  differences  between 
it  and  the  skin  of  the  palmar  surfaces.  In  what  does  the  epithelium 
of  the  dorsal  surface  differ  from  that  of  the  ventral  surface  of  the 
body? 

2.  Transitional  epithelium. 

From  a  stained  section  of  distended  bladder  made  vertical  to  its 
wall,  make  a  drawing  of  its  epithelial  lining.  How  many  cells 
thick?  What  types  of  cells  are  observable?  Why  the  name 
"transitional?"  Papillae?  Compare  this  section  with  one  from 
a  contracted  bladder  of  the  same  species  and  note  peculiarities  of 
this  epithelium  suggested  by  the  comparison. 

3.  Stratified  columnar  epithelium  (usually  ciHated). 

(a)  Non-ciliated.  An  example  of  this  variety  may  be  found  in  a 
stained  section  of  the  oral  end  of  the  large  excretory  duct  of  a 
salivary  gland. 

(b)  Ciliated.  Draw  a  small  portion  of  the  epithelial  lining  in  a  section 
of  the  trachea.  How  many  layers  of  cells?  What  is  their  position 
with  reference  to  the  lumen?  How  do  they  differ?  Goblet  cells? 
Glands?     Compare  with  type  found  in  the  epididymis. 

(c)  Action  of  cilia.  Pith  a  frog,  with  scissors  detach  the  lower  jaw 
and  with  scalpel  scrape  the  posterior  portion  of  the  mouth  cavity 
(pharynx).  Mount  the  scrapings  in  a  drop  of  physiological  salt 
solution  and  examine  under  low  and  then  under  high  power.  Note 
the  ciliary  activity  in  both  clumps  and  isolated  cells.  How  is  the 
swimming  motion  of  the  small  clumps  produced  ?  Replace  the  salt 
solution  with  a  small  drop  of  i  per  cent,  osmic  acid.  Result 
and  why?     Sketch  showing  cell-outlines  and  cilia. 

C.  Glandular  Epithelium. 

(i)  Tease  and  examine  a  bit  of  salivary  gland  or  pancreas  in  the  fresh 
condition.     Color?     Shape  of  the  cells  in  the  alveoli?     Sketch  a 
section  of   a  serous  alveolus  from  a  stained   section  of  the  sub- 
maxillary   gland    and    likewise    an    alveolus    containing    mucous 
4 


50  LABORATORY    GUIDE    FOR    HISTOLOGY. 

secreting    cells.      Differences    between    the    two?      Striations    in 
either  ? 

(2)  From  a  stained  section  of  the  cortex  of  a  kidney  draw  carefully  a 
,  few  cells  of  a  proximal  convoluted  tubule  ?     Shape  of  distal  ends 

of  cells?     Striations  and  granules? 

(3)  From  a  section  of  the  scalp  draw  a  small  area  showing  the  character 
and  structure  of  the  cells  of  a  sebaceous  gland.  Do  all  the  cells 
possess  nuclei  ?     Describe  the  functional  processes  of  these  cells. 

Upon  what  basis  is  glandular  epithelium  classified  apart  from  the  pre- 
ceding varieties?  Enumerate  the  different  structural  forms  and  functional 
varieties  of  glands. 

D.  Neuro-epithelium. 

Draw  a  taste-bud  (calyculus  gustatorius)  from  a  section  involving  the  foliate 
papillae  of  a  rabbit's  tongue  or  a  circumvallate  papilla  of  the  human  tongue. 
How  many  varieties  of  cells  compose  it  ?  Distinguishing  character  of  the  neuro- 
epithelial cells  proper? 

LITERATURE  ON  EPITHELIUM. 

ARNSTEIN,  C.  Zur  Morphologie  der  sekretorischen  Nervenendapparate.     Anat.  Anz.,  Bd. 

10,  p.  410,  1895. 
DAWSON,  P.  M.  Observations  on  the  urinary  bladder  in  man.     Johns  Hop.  Hosp.  Bui., 

Vol.  9,  p.  15s,  1898. 
DOGIEL,  A.  S.  Zur  Frage  iiber  das  Epithel  der  Harnblase.     Arch.  Mik.  Anat.,  Bd.  35,  p. 

389,  1S90. 
GURWITSCH,  A.  Die  Vorstufen  der  Flimmerzellen  und  ihre  Beziehungen  zu  Schleimzellen. 

Anat.  Anz.,  Bd.  19,  p.  44,  1901. 
HERXHEIMER,  K.  Ueber  die  Struktur  des  Protoplasmas  der  menschlichen  Epidermiszelle. 

Arch,  ftir  Mik.  Anat.,  Bd.  53,  p.  510,  1899. 
HOLMGREN,  E.  Zur  Kenntnis  der  zylindrischen  Epithelzellen.     Arch.  f.  Mik.  Anat.,  Bd. 

65,  H.  2,  p.  280,  1904. 
KOELLIKER,  A.  Ueber  die  Entstehung  des  Pigments  in  den  Oberhautgebilden.     Zeitschr. 

fiir  wiss.  ZooL,  Bd.  45,  p.  743,  1887. 
KOLOSSOW,  A.   Ueber  die  Struktur  des  Pleuroperitoneal- und  Gefassepithels  (Endothels). 

Arch,  ftir  Mik.  Anat.,  Bd.  42,  p.  318,  1893. 
KOLLOSSOW,  A.  Zur  Anatomic  und  Physiologie  der  Driisenepithelzellen.     Anat.  Anz., 

Bd.  21,  226,  1902. 
LONDON,  B.  Das  Blasenepithel  bei  verschiedenen  Fiillungszustanden  der  Blase.     Arch,  ftir 

Physiol.,  Jg.  1 88 1,  p.  317. 
MAZIARSKI,  S.  Ueber  den   Bau  und  die  Einteilung  der  Drusen.     Anat.   Hefte,  Bd.   58, 

p.  171,  1901. 
RAMOND,  M.  F.  La  desquamation  de  I'Epithelium  de  I'intestin  grele  an  cours  de  la  digestion. 

Compt.  Rend.  Soc.  de  Biol.,  T.  56,  p.  171,  1904. 
RETZIUS,  G.   Ueber  die  sensibilen  Nervendigungen  in  den  Epithelien  bei  den  Wirbeltieren. 

Biol.  Untersuch.  N.  F.  Bd.  4,  p.  37,  1892. 
SCHAEFER,  E.  A.  Theories  of  Cihary  Movement.     Anat.  Anz.,  Bd.  24,  No.  19-20,  p.  497, 

1904. 
SCHAEFER,  E.  A.  Models  to  Illustrate  Ciliary  Action.     Anat.  Anz.,  Bd.  26,  No.  19,  p.  517, 

1905. 
.SCHUBERG,  A.   Untersuchungen  iiber  zellverbindungen.     Zeit.   f.  wiss.  ZooL,  Bd.  87,  H. 

4,  P-  551.  1907- 
SOMMER,  A.  Zur  Kenntnis  des  Pericardialepithels.     Arch,  fiir  Mik.  Anat.,  Bd.  62,  1903. 
WEIDENREICH,  F.  Weitere  Mitteilungen  iiber  den  Bau  der  Hornschicht  der  menschlichen 

Epidermis  und  ihren  sogenannten  Fettgehalt.  Arch,  ftir  Mik.  Anat.,  Bd.  57,  p.  583, 

1901. 
ZIMMERMANN,  K.  W.    Beitrage  zur  Kenntnis  einiger  Drusen  und  Epithelien.  Arch,  fiir 
.     Mik.  Anat,  Bd.  52,  p.  552,  1898. 


II.  THE  SUPPORTING  AND  CONNECTIVE  TISSUES. 
(third  paper.) 

A.  Connective  Tissue  Proper. 

1.  Embryonic. 

From  a  section  of  a  small  mammalian  embryo  (lo  to  15  mm.  pig), 
sketch  under  high  power  an  area  of  the  subcutaneous  tissue.  It  is 
composed  of  distinct  cells  ?  Why  is  it  called  a  syncytium  ?  What 
occupies  the  interstices?  Compare  it  with  the  subcutaneous 
tissue  of  the  adult  (human).     Differences? 

2.  Mucuous   connective   tissue   or  "Jelly  of    Wharton."     What    is 

the  appearance  and  apparent  consistency  of  the  fresh  umbilical 
cord  ?  Under  high  power  draw  a  small  area  from  a  stained  trans- 
verse section  of  an  umbihcal  cord  (pig  or  human  near  term), 
noting  the  so-called  stellate  cells  and  their  branching  processes. 
Do  all  the  processes  anastomose?  May  this  tissue  also  be  called 
a  syncytium?  Structure  and  analogy  of  the  processes?  Structure 
of  the  interstitial  substance?  Origin  of  fibers?  Found  in  the 
adult  body? 

3.  Fibrous  connective  tissue. 

(a)  Reticular. — Examine  under  high  power  a  stained  section  of  spleen 
of  lymph  gland  which  has  been  subjected  to  digestion  or  to  "  shak- 
ing." Draw  a  small  area  showing  the  meshwork  of  fine  fibers 
from  which  the  cells  have  been  removed.  Note  trabeculae  of  coarser 
arrangement.  Size  of  the  individual  fibers?  What  determines 
size  of  meshes?  Where  else  is  reticular  tissue  found  and  how 
does  it  dift'er  from  this  ?  What  are  the  reasons  for  classifying  this 
variety  of  fibrous  tissue  separately? 

(b)  White  Fibrous. 

(i)  Areolar.  Take  a  small  mass  of  subcutaneous  or  intermuscular 
tissue  from  a  freshly  killed  mammal  and  spread  it  out  with 
needles  on  a  dry  slide  into  a  thin  film.  Let  the  edges  of  the  film 
dry  to  the  slide  but  keep  the  center  moist  by  breathing  upon  it 
now  and  then.  Put  a  drop  of  distilled  water  on  a  cover- 
glass  and  invert  it  on  the  center  of  the  film.  E.xamine  under 
high  power,  noting  the  wavy  and  taut  bundles  of  white  fibrous 
tissue  of  varying  sizes  and  running  in  various  directions;  the 

51 


52  LABORATORY    GUIDE    FOR    HISTOLOGY. 

single  elastic  fibers  of  definite  contour  and  occasionally  branch- 
ing, and  also  the  various  forms  of  "connective  tissue  corpuscles" 
in  the  interspaces,  and  occasional  migratory  cells  (granular, 
"mast"  cells  and  ordinary  leukocytes).  Then  remove  the 
cover  and  replace  the  water  with  i  per  cent,  acetic  acid. 
What  is  the  effect  of  the  acid  upon  the  white  fibrous  tissue? 
On  the  elastic  fibers  and  the  cells?  Explain  occasional  con- 
strictions of  the  bundles  of  white  fibrous  tissue.  Next,  from  a 
stained  vertical  section  of  the  skin  (human),  draw  an  area  of  the 
subcutaneous  tissue  showing  the  loosely  arrayed  bundles  of  fine 
fibrils  and  the  so-called  connective  tissue  corpuscles.  Are  the 
latter  individual  cells  ?  Explain  their  position  and  appearance. 
(2)  Tendon,  compact  white  fibrous.  Take  a  small  strand  of  tendon 
from  the  tail  of  a  rat,  stretch  it  lengthwise  on  the  slide,  letting  , 
the  ends  dry  firmly  to  the  slide,  keeping  the  strand  straight, 
but  tease  the  middle  slightly  in  a  drop  of  salt  solution.  Put 
cover-glass  over  teased  portion  and  carefully  study  the  appear- 
ances of  the  fresh  tissue.  Next,  remove  the  salt  solution  and 
replace  it  with  a  drop  of  i  per  cent,  acetic  acid,  and  note  and 
explain  the  effect  of  the  acid  and  the  coming  into  view  of  the 
columns  of  tendon  cells.  Then  wash  off  the  acetic  acid  with 
distilled  water,  place  a  drop  of  carmalum  under  the  cover-glass 
and  let  this  act  till  the  tissue  is  well  stained.  Finally,  wash  off 
the  stain,  and  mount  in  glycerin.  Draw  an  area  under  high 
power,  showing  the  fine,  wavy,  parallel  fibrillation  of  the  tendon 
bundles  and  the  chains  of  elongated  cells  with  rod-shaped  and  oval 
nuclei. 

Also  sketch  a  small  area  of  a  stained  transverse  section  of  a  ten- 
don, noting  the  areolar  sheaths  of  the  tendon  fasciculi  and  the 
irregularly  stellate  bodies  of  the  tendon  cells  in  the  section. 
What  is  the  real  shape  of  the  "tendon  cells?" 

(c)  Elastic. 

(i)  On  a  dry  slide,  spread  out  with  needles  into  a  thin  film  a  piece 
of  the  fresh  intermuscular  connective  tissue  from  the  animal 
used  above.  Make  the  film  to  cover  the  full  width  of  the  slide, 
and  let  it  dry  to  the  slide  throughout.  When  dry,  place  on  the 
center  of  the  film  a  few  drops  of  a  i  per  cent,  solution  of  magenta 
made  in  70  per  cent,  alcohol  and  add  a  small  drop  of  a  0.5  per 
cent,  aqueous  solution  of  gentian  violet.  Let  the  mixture  act 
about  two  minutes,  then  drain  it  off  and  put  on  a  drop  of  glycerin 
and  examine  at  once;  or,  after  draining,  let  the  preparation  dry 
throughout  and  mount  in  balsam.  Explain  the  deep  staining 
of  the  elastic  fibers  by  the  alcoholic  magenta.     By  what  other 


HYALINE    CARTILAGE.  53 

•  characters  may  they  be  distinguished  from  the  white  fibrous 

tissue?  Sketch  a  field  including  both  varieties  of  fibrous  tissue 
and  whatever  cells  present.  What  can  be  said  of  the  size  and 
relative  abundance  of  the  elastic  fibers  ?  Nature  of  their  sheaths  ? 
(2)  On  the  slide,  in  a  drop  of  glycerin  slightly  colored  with  alcoholic 
magenta,  tease  a  small  shred  of  the  ligamentum  nuchae  of  the  ox. 
Cover  and  note  the  well  defined  elastic  fibers  constantly  branching 
and  anastomosing  with  one  another.  Look  for  transverse 
marking  on  the  fibers.  Draw,  illustrating  arrangement. 
Also  draw  a  small  area  of  a  stained  transverse  section  of  liga- 
mentum nuchae.  What  is  the  shape  of  the  fibers  in  cross-section  ? 
What  occupies  the  spaces  between  them? 

(d)   The  Neuroglia. 

(i)  From  a  section  of  the  human  cerebral  cortex,  or  spinal  cord, 
stained  by  the  Golgi  (silver  nitrate)  method,  draw  one  or  two 
"neuroglia cells."  Note  the  general  spider-shape  of  the  cell  and 
the  apparent  relation  of  the  processes  to  the  cell-body.  Varieties  ? 
Are  they,  in  reality,  cells? 

(2)  From  a  section  of  the  human  spinal  cord  stained  by  the  Benda 
neuroglia  method,  draw  a  "neuroglia  cell"  using  oil  immersion 
lens.  WTiat  is  the  difference  between  the  tissue  when  stained 
in  this  way  and  when  stained  by  the  Golgi  method?  What  is 
the  relation  of  the  neuroglia  fibers  to  the  cells  and  neuclei? 
Apply  the  idea  of  the  syncytium  in  the  development  of  the  tissue. 
Do  all  the    "cells"  studied  in  (i)  above  contain  nuclei? 

(3)  From  the  section  used  in  (2),  draw  a  few  of  the  epithelial  cells 
(ependyma  cells)  lining  in  the  central  canal.  Are  they  ciliated? 
Actual  cell  membranes?  Do  they  send  out  processes?  General 
arrangements?  What  and  where  found  is  the  substantia  gela- 
tinosa?  If  the  section  of  the  human  cord  fails  to  show  the 
ependyma  cells  well,  on  account  of  occlusion  of  the  central  canal 
the  spinal  cord  of  the  hog  or  dog  may  be  used  instead. 

B.  Cartilage. 

1.  "Pre-cartilage"  (embryonic  cartilage).     Draw  a  small  area,  show- 

ing an  early  stage  of  cartilage  as  it  appears  in  a  stained  section  of  a 
vertebrate  embryo  [section  used  in  A,  i,  (a)  above].  What  is  the 
relation  of  the  cells  to  each  other?  Shape  ?  What  is  the  nature  and 
origin  of  the  matrix  or  intercellular  substance  ?  Significance  of  the 
capsules  ? 

2.  Hyaline  cartilage. 

(a)  Articular   cartilage.     Cut   a   very   thin   tangential   section   of   the 
cartilage  covering  the  articular  surface  of  the  end  of  a  long  bone 


54  LABORATORY    GUIDE    FOR    HISTOLOGY. 

freshly  obtained  (from  the  butcher),  taking  a  section  (i)  from  near 
the  edge  of  the  joint,  and  (2)  one  away  from  the  edge.  Treat  the 
sections  2  to  4  minutes  with  i  per  cent,  acetic  acid,  then  wash  in 
water,  mount  in  glyerin  and  examine.  What  is  the  shape  and 
arrangement  of  the  capsules  and  of  the  cartilage  cells  situated  in 
the  lacunae?  Do  the  cells  fill  the  lacunae?  Are  there  any  indi- 
cations of  multiplication  of  cartilage  cells?  What  is  the  nature  of 
the  matrix  in  the  second  section  ?  Note  the  gradation  from  fibrous 
connective  tissue  into  cartilage  (transitional  cartilage)  as  shown  by 
the  presence  of  connective  tissue  fibers  from  the  synovial  membrane 
in  the  matrix  of  the  first  section  taken.  Compare  with  stained 
section  issued.  Make  drawings  of  small  areas  from  each  region, 
(b)  Costal  cartilage.  Under  low  power,  examine  a  stained  transverse 
section  of  rib-cartilage  (human  or  dog).  What  is  the  relation  of 
the  perichondrium  to  the  cartilage?  What  is  the  arrangement 
of  the  cartilage  cells  lying  just  under  the  perichondrium?  What 
may  this  arrangement  indicate?  Are  there  blood-vessels  in  the 
cartilage?  In  the  perichondrium?  Draw,  showing  relations  and 
arrangements.  Under  high  power,  draw  a  small  area  from  near 
the  center  of  the  section.  How  are  the  cells  arranged?  What  is 
the  nature  of  the  matrix  ?  Any  indications  of  a  fibrillar  structure  ? 
Why  classified  as  hyalin?  If  tendency  toward  ossification  is 
indicated,  where?  Difference  in  this  respect  between  human 
costal  cartilage  and  that  of  most  animals? 

3.  Fibro-cartilage. 

(a)  White  fibro-cartilage. 

(i)  Make  a  thin  vertical  section  from  a  fresh  intervertebral  disk 
(dog  or  ox)  or  a  transverse  section  from  a  semilunar  cartilage  of 
the  knee-joint.  Place  on  the  slide  and  treat  with  Lugol's  solution, 
diluted  one-half,  5  minutes.  The  iodine  stains  the  cell  because 
of  the  glycogen  in  it,  but  leaves  the  matrix  unstained.  Does  the 
capsule  show  any  concentric  markings?  What  is  the  nature 
of  the  matrix? 

(2)  From  a  stained  section  passing  longitudinally  through  the  inser- 
tion of  the  ligamentum  teres  into  the  head  of  the  femur,  make  a 
narrow  drawing  showing  the  transition  of  hyaline  articular 
cartilage  into  white  libro-cartilage.  Under  high  power,  draw  a 
small  area  of  the  white  fibro-cartilage.  Shape  of  cells  and  rela- 
tion of  cells  to  fibers  ?     Endoplasm  ?     Interfibrillar  matrix  ? 

(b)  Elastic  (yellow)  fibro-cartilage. 

From   a   specially   stained   section   of   the   external   ear   (human, 
monkey,  hog  or  ox),  draw,  under  high  power,  a  small  area  show- 


MACERATED    BONE.  55 

ing  the  size  and  arrangement  of  the  cells  and  the  nature  of  the 
matrix.  Are  both  white  and  elastic  fibers  present?  xA.re  there 
cells  in  the  process  of  division?  Interfibrillar  matrix?  What 
is  the  color  of  this  cartilage  in  the  fresh  state?  Why?  The 
external  ear  of  the  ox  contains  coarser  fibers  than  most  animals 
while  that  of  the  rat  and  mouse  shows  practically  no  fibers. 

C.  Bone. 

1.  Compact  and  spongy  or  cancellous  bone,  macroscopic  appearance. 

With  the  naked  eye  or  hand-lens  examine  the  structure  of  a  long 
bone  (human  femur  preferable),  which  has  been  sawed  longitud- 
inally through  epiphysis  and  diaphysis.  Make  a  sketch  showing 
the  gross  structural  difference  between  the  two  localities,  giving 
some  attention  to  the  architecture  of  the  cancellous  bone  of  the 
epiphysis. 

2.  Decalcified  bone. 

From  a  thin  transverse  section  through  the  shaft  of  a  small  long 
bone,  stained  by  the  Van  Gieson  method,  make  a  drawing  under 
low  power  of  a  narrow  segment  passing  from  marrow  cavity  to 
periphery.  Note  (a),  the  periosteum  and  fibers  of  Sharpey  and 
their  relation  to  the  bone;  (b),  the  lamellae  of  the  bone  struc- 
ture, namely,  the  perimeduUary  or  inner  circumferential  lamellee; 
periosteal  or  outer  circumferential  lamellae;  the  Haversian  systems, 
and  the  interhaversian  areas.  Is  the  periosteum  arranged  in  layers  ? 
How  are  the  bone  cells  or  corpuscles  arranged?  What  is  their 
shape?  What  constitutes  the  lamella;?  By  what  is  an  Haver- 
sian canal  occupied  ?  General  structure  of  osseous  matrix  ?  What 
is  the  arrangement  of  the  connective  tissue  fibers  of  the  lamellae  ? 

3.  Macerated  bone. — Ground  section. 

(a)  With  a  fine  saw,  cut  as  thin  a  disk  as  possible  from  the  shaft  of  a 
long  bone  which  has  been  boiled  in  an  alkaline  solution  till  nearly 
white  when  dry,  or  one  from  an  ordinary  skeleton.  Grind  it  be- 
tween two  hones  until  thin  enough  for  fine  print  to  be  easily  read 
through  it.  Wash  ofi'  the  debris  with  water,  soak  in  two  changes 
of  absolute  alcohol  20  minutes,  then  in  a  bottle  containing  pure 
ether  12  hours  or  longer,  to  extract  the  remaining  t)il.  Let  dry 
thoroughly,  keeping  it  clamped  between  two  slides  to  prevent 
warping.  To  mount,  first  heat  a  small  drop  of  balsam  on  a  slide 
until,  when  cool,  it  is  hard  enough  to  be  merely  dented  with  the 
finger  nail.  Then  place  the  bone  section  ujjon  the  hardened 
balsam,  lay  the  cover-glass  on  it,  gently  warm  till  the  balsam  be- 
comes plastic  and  then  firmly  press  down  the  cover.     Do  not  heat 


56  LABORATORY    GUIDE    FOR    HISTOLOGY. 

SO   far  that   the   balsam    is    thin    enough    to    penetrate   the   bone 
structure. 

(b)  Examine  under  low  power  and  determine  the  various  systems 
of  lamellae  studied  in  2  (b)  above.  What  differences  in  appear- 
ance are  to  be  noted  ?  Sketch  a  narrow  segment.  Significance  of 
interhaversian  area? 

(c)  Under  high  power  make  a  detailed  drawing  of  an  Haversian 
system.  What  are  the  lacunae?  Canaliculi?  Do  the  canaliculi 
anastomose?  Do  they  communicate  with  those  of  neighboring 
systems?  Examine  a  longitudinal  section  and  determine  the 
direction  and  relationship  of  the  Haversian  canals,  and  the  direction 
of  the  long  axes  of  the  lacunse.  Make  a  sketch  illustrating  the 
shape  of  the  bone  corpuscle.     Differences  of  its  three  axes  ? 

*        4.  Development  of  bone. 

From  a  stained  longitudinal  section  of  a  limb  of  a  fetal  pig  of  about 
four  centimeters  stained  by  Van  Gieson's  method,  or  of  a  finger  of  a  human 
fetus,  draw  under  low  power  the  appearance  presented  by  a  median 
section  of  one  of  the  long  bones  (now  chiefly  cartilage).  Some  of  the 
stages  of  both  the  endochondral  and  the  intramembraneous  form  of  bone 
development  may  be  observed  in  the  same  section.  Near  the  middle  of 
the  shaft  or  diaphysis  note  the  locality  of  the  center  of  ossification  with 
its  primary  medullary  spaces  and  different  forms  of  cells.  Note  the 
transition  of  the  perichondrium  into  a  periosteum  with  outer  fibrous  and 
inner  thick,  osteogenetic  layers.  Look  for  ingrowths  of  osteogenetic 
tissue  (periosteal  buds).  From  the  epiphysis  toward  the  center,  note 
the  characteristic  changes  in  the  shape,  size  and  arrangement  of  the 
cartilage  cells.  Identify  "calcifying  cartilage  matrix."  Under  high 
power  identify  "osteoblasts,"  and  "osteoclasts."  Draw  small  areas 
showing  each  in  their  positions.  Also  draw  illustrating  the  intramem- 
braneous bone  formation  taking  place  under  the  periosteum.  By 
which  process  is  the  shaft  of  the  bone  formed  ?  The  epiphysis  ?  Is 
cartilage  transformed  into  bone  or  replaced  by  bone  ? 

D.  Adipose  Tissue. 

1.  From  the  subcutaneous  connective  tissue  in  the  stained  section  of  the 
skin  pre\dously  used,  or  from  any  of  the  previous  preparations  con- 
taining them,  sketch  a  few  fat  cells  showing  the  position  of  nucleus  and 
cytoplasm.  In  this  section  and  in  the  section  of  fetal  material  used 
above,  look  for  cells  in  the  process  of  fat  formation.  Describe  the 
process  from  its  earliest  stage  to  the  fully  developed  fat  cell.  Origin 
of  the  cells  ?     What  changes  occur  during  emaciation  ? 

2.  On  a  dry  slide,  spread  with  needles  a  film  of  fresh  intermuscular 
tissue  containing  fat.     Upon  the  center  place  a  drop  of  i   per  cent. 


ADIPOSE    TISSUE.  57 

osmic  acid  and  let  it  act  lo  minutes.     Action  of  the  acid?     Why?     Its 
use  as  a  test  in  pathology? 

3.  To  another  fresh  film,  or  one  taken  from  a  specimen  preserved  in 
formalin,  add  a  drop  or  two  of  saturated  solution  of  Sudan  III  in  70 
per  cent,  alcohol  (or  Scharlack  R.).  Let  this  act  10  minutes,  wash  off 
with  70  per  cent  alcohol,  stain  10  minutes  with  dilute  hematoxylin,  wash 
again,  mount  in  glycerin,  and  examine  under  both  low  and  high  power. 
What  is  the  peculiar  action  of  the  Sudan  III  (or  Scharlack  R.)  ?  Its 
use  as  a  test  in  pathology  ?     What  is  stained  by  the  hemotoxylin  ? 

4.  Study  a  digested  preparation  which  contained  adipose  tissue.  What 
is  the  nature  of  the  capsules  or  cell  membranes  ?  Draw  one  or  two 
under  high  power. 

LITERATURE  ON  THE  SUPPORTING  AND  CONNECTIVE  TISSUES. 
Development. 
BARDEEN,  C.  R.  Studies  of  the  Development  of  the  Human  Skeleton.     Am.  Jour.  Anat. 

Vol.  4,  No.  3,  p.  265,  1905. 
COFFEY,  D.  J.  The  Development  of  the  Fat  Cell.  Trans.  R.  Acad,  of  Med.  in  Ireland,  \'oL 

24,  p.  468,  1906. 
HIS,  W.  Ueber  Zellen-  und  Syncytienbildung.     Studien  an  Salamander  Keim.     Abhandl.  d. 

Math.-Physik.   Classe  der  Kgl.   Sach.   Gesells.  der  Wissenschaften.  Bd.  24,  1898. 
KORFF,  K.  Die  Analogie  in  der  Entwickelung  der  Knochen-  und  Zahnbeingrundsubstanz 

der  Saugetiere  nebst  kritischen  Bemerkungen  iiber  die  Osteoblasten-  und  Odontoblas- 

tentheorie.     Arch.  f.  Mik.  Anat.,  Bd.  69,  H.  3,  p.  457,  1906. 
LOEWENTHAL,  U.  Beitrag  zur  Kenntnis  der  Struktur  und  der  Teilung  von  Bindegewebs- 

zellen.     Arch,  fiir  Mik.  Anat.,  Bd.  63,  H.  2,  p.  389,  1903. 
MALL,  F.  P.  On  the  Development  of  the  Connective  Tissues  from  the  Connective-tissue 

Syncytium.     Am.  Jour,  of  Anat.,  Vol.  i,  No.  3,  1902. 
PROWAZCK,  S.  Ein  Beitrag  zur  Genese  des  Pigments.  Zool.  Anz.,  Bd.  31,  No.  25,  p.  863, 

1907- 
RETTERER,    E.  Histogenese   du   tissu   reticule   aux   depens   de    I'epithelium.     \'erhandl. 

der  anat.  Gesellsch.,  Bd.  11,  p.  25,  1897. 
RETTERER,    E.  Histogenese   des   tissues   fibreux   et   fobro-cartilageneux.     Compt.  rend. 

Soc.  Biol.,  T.  58,  No.  6.  p.  240,  1905. 

Connective  Tissues  Proper. 

.\RAI,  H.  Die  Blutgefasse  der  Sehnen.     Anat.  Hefte,  H.  103,  .\bt.  i,  p.  363,  1907. 
BRANSON,  L.  H.  The  Syncytium.     Jour.  Am.  Med.  Assoc,  Vol.  49,  No.  13,  p.  11 10,  1907. 
CHITTENDEN,  R.  H.,  and  GIES,  W.  J.  The  Mucin  of  White  Fbrous  Connective  Tissue. 

Jour,  of  Exper.  Med.,  Vol.  i,  No.  i,  1896. 
DOBBERTIN,  R.  Ueber  die  Verbrsitung  und  Anordnung  des  elastischen  Gewebes  in  den 

Schichten  des  gesamten  Darmkanals.     Gekronte  Preisschrift.  Rostock,  1896. 
FLINT,  J.  M.  The  Connective  Tissue  of  the  Salivary  Glands  and  Pancreas  with  its  Develop- 
ment in  the  Glandula  Submaxillaris.  Johns  Hopkins  Hospital  Reports,  Vol.  12,  1904, 
GEMMIL,  J.  T.  Notes  on  (a)  the  Origin  of  Elastic  Fibres  in  Tendon,  (b)  Branching  of 

Young  Tendon  Cells.     Jour.  Anat.  and  Physiol.  Vol.  40,  Pt.  4,  1906. 
MAGRATH,  G.  B.    Observations   upon  the   Elastic  Tissue   of   Certain   Human   Arteries. 

Jour.  Bost.  Soc.  Med.  Sc.  Vol.  3,  p.  139,  1899. 
MALL,  F.  P.  Reticulated  Tissue  and  its  Relation  to  the  Connective  Tissue  Fibrils.     Johns 

Hop.  Hos.  Reports,  Vol.  i,  p.  171,  1896. 
POSNER,  E.  R.,  and  GIES,  W.  J.    A  Prehminary  Study  of  the  DigestibiHty  of  Connective 

Tissue  Mucoids  in  Pepsin-hydrochloric  Acid.     Am.  Jour.  Physiol.,  Vol.  9,  p.  330, 

1904. 
RENAUT,  J.  Sur  une  nouvelle  fonction  glandulaire  des  cellules  fLxes  du  tissu  conjonctif — 

la  fonction  rhagiocrine.     Bui.  de  I'acad.  de  Med.,  March,  1906. 
SCHAEFFER,    J.  Grundsubstanz,  Intercellularsubstanz,  und  Kittsubstanz.     .\nat.    Anz. 

Bd.  19,  p.  95,  1901. 
SPULER,  A.  Beitrage  zur  histologic  und  histiogenese  der  Binde-  und  Stutzsubstanz.     .\na- 

tomische  Hefte,  Bd.  7,  1897 


58  LABORATORY    GUIDE    FOR    HISTOLOGY. 

THOMASS,  W.  f  eber  die  Histologic  der  menschlichen  Nabelschnur  mit  besonderer  Beriick- 
sichtigung  der  Allantois  und  des  Dottergangs.  Inaugural  Dissertation.  Gustav 
Schade,  Berlin,  1900. 

Neuroglia. 

BEXDA,  C.  L'eber  die  Flimmerzellen  des  Ependyms  nach  LTntersuchungen  von  Dr.  Salaman 

und  Hans  Richter.     Arch.  f.  Anat.  u.  Physiol.,  Physiol.  Abt.,  Jg.  1905,  H.  1-2,  p.  27. 
BONOME,  A.  Sull'istogenesi  della  neuroglia  normale  nei  vertebrati.     Arch.  Ital.  de  Anat.  ed 

Ambryol.,  Vol.  6,  No.  2,  p.  257,  1907. 
FURNER,  J.  A  Note  Concerning  Mesoglia  Cells.     Rev.  of  Neurol,  and  Psychiatry,  Vol. 

3.  P-  773.  1906. 
HARDESTY,  I.  On  the  Development  and  Nature  of  the  Neuroglia.     Am.  Jour,  of  Anat. 

Vol.  3,  No.  3,  1904. 
HUBER,  G.  C.  Studies  on  Neuroglia  Tissue.     Contributions  to  Medical  Research,  Univ. 

of  Michigan,  June,  1903. 
ROSENZWEIG,  E.  Beitrage  zur  Kenntnis  des  feineren  Baues  der  Substantia  Rolandi  des 

Riickenmarks.     Jour,  of  Psychol,  u.  Neurol.,  Bd.  5,  H.  2,  p.  49,  1905. 
SPIELME\TiR,  W.  Von  der  protoplasmatischen  und  faserigen  Stutzsubstanz  des  Central- 

nervensystems.     Arch.  f.  Psychiat.  u.  Nervenkr.,  Bd.  42,  H.  2,  p.  303,  1907. 
STUDNICKA,  F.  K.   L^ntersuchungen  liber  den  Bau  des  Ependyms  der  Nervosen  Central- 

organe.     Anatomische  Hefte,  Bd.  15,  p.  301,  1900. 
TERRY,  R.  J.  A  Neuroglia  Syncytium  in  Betrachus  (Opsanus  tau).  Anat.  Anz.,  Bd.  31,  No. 

50,  p.  79,  1907. 
WEIGERT,  C.  Beitrage  zur  Kentniss  der   normalen    menschlichen  Neuroglia.     Abhandl. 

der  Senckenbergischen  Naturforsch.  Gesellsch.,  Bd.  19,  1895. 

Cartilage. 

HANSEN,  F.  C.  C.  Untersuchungen  uber  die  Gruppe  der  Bindesubstanzen.     I.  Der  Hyalin- 

knorpel.     Anat.  Hefte,  H.  83  (Bd.  27,  H.  3),  p.  535,  1905. 
LOSSEN,  J.  Anatomische  Untersuchungen  liber  die  Cartilagines  cuneiformes  (Wrisbergische 

Knorpel).     Inaugural  Dissertation.     M.  Liedtke,  Konigsberg,  1900. 
MORAWITZ,    P.    Zur    Kentniss   der   Knorpelkapseln   und    Chrondrinballen  des   hyalinen 

Knorpels.  Arch,  flir  Mik.  Anat.,  Bd.  60,  H.  i,  1902. 
SCHAFFER,  J.  Knorpel  Kapseln  und  Chrondrinballen.     Anat.  Anz.,  Bd.  23,  p.  524,  1903. 
STUDNICKA,    F.    K.  Ueber   kollagene    Bindegewebsfibrillen   in   der    Grundsubstanz   des 

Hyalinknorpels,  im  Dentin   und  im  Knochengewebe.      Anat.   Anz.,   Bd.    29,   No. 

13-14,  P-  334,  1906. 
WENDELSTADT,  Dr.  Experimentelle  Studie  liber  Regenerationsvorgange  am  Knochen 

und  Knorpel.     Arch,  flir  Mik.  Anat.,  Bd.  63,  H.  4,  1904. 

Bone. 

CZERMAK,  N.  Vergleichende  Studien  liber  die  Entwicklung  des  Knochen-  und  Knorpel- 

gewebes.     Anat.  Anz.,  Bd.  3,  p.  470,  1888. 
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Mik.  Anat.,  Bd.  29,  p.  213,  1887. 
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66,  p.  471,  1905. 
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117,  1896. 


E.  BLOOD  AND  LYMPH. 

(fourth  paper.) 

I.  General  composition  of  blood. 

(a)  Thoroughly  clean  a  slide  and  cover-glass.     With  a  sterilized  needle 

or  spring-lancet  prick  the  ear  or  the  end  of  the  finger  which  also  has 
been  just  previously  bathed  with  ether-alcohol  and  thoroughly  dried. 
Place  a  small  drop  of  blood  on  the  slide  and  quickly  put  on  the 
cover.  Examine  at  once.  How  many  and  what  are  the  general 
morphological  constitutents  ?  How  are  the  red  corpuscles  (eryth- 
rocytes) arranged?  Explain  the  arrangement.  Does  it  occur  in 
the  circulation  ?  Tap  the  cover  with  needle  and  observe  the  color- 
less corpuscles  sticking  to  the  slide.  Which  variety  of  corpuscles 
is  the  more  numerous?  Watch  an  individual  white  corpuscle. 
Does  it  change  shape?  Ameboid  movement?  Elementary  cor- 
puscles or  blood  platelets?  Shape?  Fibrin  filaments?  Sketch 
one  of  the  rouleaux  of  red  corpuscles  and  three  or  four  white  cor- 
puscles.    Do  the  corpuscles  vary  in  size? 

(b)  Make  another  mount  by  adding  fresh  blood  to  a  drop  of  Toisson's 
solution  on  a  cover-glass.  Sketch  a  red  blood  corpuscle  lying  flat, 
and  also  one  in  profile.  Shape?  Central  pallor?  Nucleated? 
Measure  20  red  corpuscles  and  20  white,  and  determine  the  average 
diameter  of  each  variety. 

Note. — For  measuring  objects  under  the  microscope,  take  a  ''  stage 
micrometer"  having  on  it  one  millimeter  ruled  into  hundredths,  and 
with  it,  carefully  determine  the  value  of  the  spaces  or  di^■isions  of  the 
arbitrary  scale  ruled  on  an  "ocular  micrometer."  The  dimensions 
of  the  spaces  of  the  stage  micrometer  being  known,  the  size  of  the 
object,  which,  with  a  given  magnification  will  occupy  one  or  more 
divisions  of  the  ocular  micrometer,  is  easily  calculated.  With 
draw-tube  at  a  given  position,  determine  the  value  for  both  a  high 
and  a  low  power  objective.  The  unit  of  measurement  is  the 
micromillimeter,  or  yoVo"  o^  ^  millimeter. 

(c)  From  the  slide  used  above,  also  sketch  a  "crenated"  red  corpuscle. 
W^hat  is  the  cause  of  the  crenation?  The  crenation  illustrates  a 
pathological  form  observed  in  '' ^laragliano's  degeneration." 
In  a  corpuscle  which  has  not  undergone  crenation,  note  the  enlarge- 
ment of  the  central  pallor  (endo-globular  degeneration).     Why? 

59 


6o  LABORATORY   GUIDE    FOR   HISTOLOGY. 

2.  Blood    platelets    (elementary    corpuscles).      Stained    preparation. 

Cleanse  the  finger,  place  on  a  small  drop  of  a  freshly  made  i  per 
cent,  solution  of  methyl  violet  in  normal  salt,  and  prick  the  finger 
through  the  drop  so  that,  as  the  blood  exudes  and  mixes  with  the 
stain,  the  plate  lets  are  stained.  Mount  and  examine  under  high 
power.  Sketch  a  few  platelets  showing  shape  and  relative  size. 
What  are  they?  Tendency  to  collect  in  clumps?  Note  the 
white  blood  corpuscles  which  are  also  stained,  and  the  shape  of 
their  nuclei. 

3.  Fibrin.     Stained  preparation. 

On  a  carefully  cleaned  cover-glass,  draw  a  drop  of  blood,  and 
immediately  spread  it  out  thin.  Put  aside  in  a  moist  chamber 
(invert  a  wet  watch  glass  over  it)  15  minutes  to  coagulate.  Then 
let  dry  at  the  edges  and  carefully  place  in  a  watch  glass  of  distilled 
water  for  5  to  10  minutes.  Drain  off  the  water,  place  in  70  per 
cent,  alcohol  5  minutes  or  longer,  drain,  and  then  put  on  a  drop  of 
I  per  cent,  acqueous  methyl  violet.  Let  this  act  5  minutes,  rinse 
with  water,  and  treat  in  a  similar  way  with  i  per  cent,  eosin.  Again 
rinse  in  water  and  let  the  preparation  dry  thoroughly,  and  mount 
in  balsam.  Sketch  a  small  part  of  a  field  showing  arrangement  of 
fibrin  filaments,  etc.  Are  blood  platelets  more  numerous  than  in 
2,  above?  Why?  Relation  of  fibrin  filaments  to  clumps  of  plate- 
lets? 

4.  Blood  pigment. 

(a)  To  a  mount  of  fresh  blood,  add,  at  edge  of  cover-glass,  a  drop  of 
distilled  water  and  examine  under  high  power.  What  is  the  effect 
of  the  water  on  the  shape,  size  and  color  of  the  red  corpuscles  ? 

(b)  To  a  mount  of  fresh  blood  add  a  drop  of  i  per  cent,  tannic  acid 
and  cover.  What  action  does  the  acid  have  upon  the  coloring 
matter  of  the  corpuscle ?     Why?     Sketch,  showing  effect. 

(c)  Blood  crystals. 

(i)  Hemaglobin  crystals.  Put  a  large  drop  of  mammalian  blood, 
preferably  that  of  the  rat,  on  the  slide,  and  let  dry  without 
covering.  When  dry,  add  a  drop  of  distilled  water  and  cover. 
Let  dry  and  examine.  When  dry,  the  preparation  may  be  mounted 
in  balsam.  What  as  to  the  sizes,  shapes  and  color  of  the  crystals  ? 
Sketch  a  few.     Why  was  the  water  added? 

(2)  Hemin  crystals.  Put  a  large  drop  of  human  blood  on  the  slide  and 
let  dry  thoroughly.  Then  place  on  it  a  small  crystal  of  sodium 
chlorid  and  a  drop  of  glacial  acetic  acid.  Stir  with  a  clean  glass 
rod  for  about  a  minute  and  then  dry  by  holding  the  slide  high 
above  a  small  Bunsen   flame.     Examine,   and  if  unsuccessful. 


WHITE    BLOOD    CORPUSCLES.  6l 

repeat  the  application  of  the  acid  and  the  stirring.  When 
successful,  dry  thoroughly  and  mount  in  balsam.  Examine  under 
high  power.  How  do  the  hemin  crystals  differ  in  form  and  size  ? 
Color?  How  do  they  differ  from  hemaglobin  crystals,  and  from 
the  crystals  of  sodium  chlorid  ?  Sketch  a  cluster  and  one  or  two 
lying  singly. 

5.  White  blood  corpuscles. 

Two  consecutive  hours  are  necessary  to  make  preparations  by  the 
Ehrlich  method  for  the  study  of  the  different  kinds  of  white 
corpuscles.     The  steps  in  this  method  are  as  follows: 

(a)  Put  a  Bunsen  flame  under  the  tapered  end  of  the  copper  bar,  fur- 
nished, and,  when  hot,  without  removing  the  tiame,  clean  the  bar 
thoroughly. 

(b)  When  the  bar  has  been  heating  fifteen  or  twenty  minutes,  or  till 
equilibrium  is  established  between  the  radiation  and  the  absorp- 
tion of  heat,  run  a  thin  stream  of  water  along  it  toward  the  flame, 
and  mark  the  point  at  which  the  water  boils. 

(c)  Thoroughly  clean  four  cover-glasses.  Get  a  film  of  blood  on  each 
by  enclosing  a  drop  of  blood  between  two  covers  and  carefully 
drawing  them  apart.  Place  the  covers,  film  side  up,  on  the  bar  in 
line  about  three-fourths  of  an  inch  nearer  to  the  flame  than  the  line 
at  which  the  water  boils.  This  will  expose  them  to  a  temperature 
of  about  120°  C.  Protect  them  from  dust  and  let  them  remain  sub- 
jected to  the  heat  for  at  least  one  and  one-half  hours.  An  oven  with 
thermometer  may  be  used  for  the  fixation. 

(d)  The  "fixation  by  heat"  complete,  remove  the  covers,  lay  them  level, 
film  side  up,  and  cover  the  films  with  "  Ehrlich's  triple  stain." 
When  this  has  acted  10  to  15  minutes,  rinse  off"  the  surplus  stain  by 
holding  each  cover  in  forceps  and  dipping  it  through  distilled  water 
3  or  4  times.  Then  dry  the  preparation  thoroughly  by  holding  it, 
edge  downwa,rd,  high  above  the  flame  and,  when  dry,  mount  in 
balsam  on  the  slide.  The  washing  through  water  should  cease 
when  the  greater  part  of  the  film  appears  a  light  reddish  orange 
by  transmitted  light. 

(e)  In  a  similar  way  prepare  two  other  films  and  fix  them  in  ether- 
alcohol  ^  to  2  hours.  Then  rinse  consecutively  in  95  per  cent.,  80 
per  cent,  and  50  per  cent,  alcohol  and  then,  in  a  closed  vessel, 
stain  from  2  to  24  hours  in  dilute  Ehrlich's  hematoxylin  to  which 
0.5  per  cent,  of  eosin  has  been  added.  Wash  with  water,  dip  through 
70  per  cent,  and  then  95  per  cent,  alcohol,  dry  or  clear,  and  mount  in 
balsam. 

From  these  6  preparations  distinguish  and  sketch  the  following 
five  varieties  of  white  corpuscles  (Ehrlich's  classification): 


62  LABORATORY    GUIDE    FOR    HISTOLOGY. 

(i)  Small  mononuclear  (basophil  cytoplasm  with  no  granules). 

(2)  Large  mononuclear  (basophil). 

(3)  Transitional  form  (small  neutrophil  granules). 

(4)  Polymorphic  nuclei  (neutrophil)  and 

(5)  Eosinophil. 

What   is    the    color   of    the   red   corpuscles?      Why?     Are  there 
nucleated  erythrocytes  ?     What  are  myelocytes  ? 
(f)  Many  methods  of  staining  and  fixing  white  blood  corpuscles  are  in 
use,  but  descriptions  of  the  results  obtained  with  any  are  usually 
based  upon  Ehrlich's  classification  and  the  appearances  obtained 
with  the  Ehrlich  method.      A  more  rapid  method  and  one  more 
readily,  and  quite  generally,  applied  in  practical  work  is  Wright's 
modification  of  Leishmann's  method.     With  this  method,  the  films, 
may  be  made  in  the  usual  way,  whenever  convenient,  and  allowed 
to  dry  in  the  air,  and  then,  if  kept  dry  and  protected,  they  remain 
stainable  for  days  or  even  weeks.     This  method  is  as  follows: 
(i)  Make  cover-glass  films  of  blood  as  in  (c)  above,  and  let  dry  at 
room  temperature. 

(2)  Using  one  film  at  the  time,  pour  2  or  3  drops  of  Wright's  stain 
on  the  film  and  allow  it  to  act  alone,  one  minute. 

(3)  Then  add,  to  the  stain  on  the  film,  distilled  water,  drop  by  drop, 
till  the  mixture  becomes  translucent  and  a  delicate,  yellowish, 
metallic  scum  forms  on  the  surface.  Do  not  dilute  until  the  stain 
becomes  transparent.     Let  this  mixture  act  two  or  three  minutes. 

(4)  Decolorize  by  dipping  through  distilled  water  till  the  film  in  its 
thinner  portions  appears  a  pinkish  orange  by  transmitted 
light,  with  practically  no  bluish  tinge.  It  is  blue  at  first.  The 
color  of  the  thicker  portions  is  disregarded. 

(5)  Remove  the  surplus  water  by  draining  and  light  application  of 
filter  paper,  dry  at  room  temperature,  or  by  gently  warming,  and 
mount  in  balsam  on  the  slide. 

6.  Comparative. 

Make  cover-glass  preparations  as  in  5  (e)  of  both  frog's  blood  and 
bird's  blood.  Study  the  red  and  white  corpuscles  carefully  and 
determine  in  what  features  they  differ  from  the  mammalin  (human) 
and  from  each  other.  Sketch  a  few  red  corpuscles  from  each 
preparation. 

7.  Determination  of  the  number  of  blood  corpuscles. 

(a)  0/  red  corpuscles. 

Of  the  many  devices  for  blood  counting,  the  Thoma-Zeiss  hemo- 
cytometer  is  chosen  as  the  most  practical  and  accurate.     Ask  for 


NUMBER    OF    BLOOD    CORPUSCLES.  63 

instruction  at  all  doubtful  points  and  exercise  especial  care  in  the 
following: 

(i)  In  cleaning  the  pipettes. 

(2)  In  cleaning  the  counting  chamber. 

(3)  In  diluting  the  blood. 

(4)  In  mixing,  as  the  blood  is  drawn,   after  it  is  drawn,   and 
before  each  count. 

Dilute  with  Toisson's  solution.     One  part  of  blood  to  200  parts 
of  fluid  will  be  found  a  workable  ratio  for  normal  blood. 

Formula  for  the  determination  of  the  number  of  red  corpuscles  with  Thoma- 
Zeiss  apparatus. 

Let  X  =  number  of  red  cells  per  cu.  mm.,  the  unit  volume  usually  employed. 
Let  Y  =  total  number  counted  in  given  number  of  squares  (X). 
Let  N=number  of  squares  counted  (usually  200  squares). 

Then  —  =  average  number  of  corpuscles  per  square. 

Each  square  has  sides  of  2V  i^^^i-  a-^d,  therefore,  has  an  area  of  ^^y-  sq.  mm. 
Then,  number  in  i  square  multiplied  by  400  gives  number  in  i  sq.  mm. 

YTj- i^in- =  thickness  of  film  in  counting  chamber.      Therefore,-^     X     400 

(area  of  film),  multiplied  by  10  gives  the  number  in  one  cu.  mm.  of  diluted 
blood. 

-^r,^  =  the  dilution.     Therefore,  the  last  result  multiplied  by  200  will  give 
the  actual  value. 

Thus,  ^  X  4°o  X  io  X  200  =  X,  or  4000  Y  =  X. 

Make  several  counts.     If  results  are  approximate  take  the  average.     Discard 
all  doubtful  results. 

(b)  0/  white  corpuscles. 

Use  same  apparatus  as  for  red  cells,  but  use  pipette  indicated  for 
white  cells.  Exercise  the  same  care  as  for  red  cells.  Use  0.5 
percent,  acetic  acid  for  the  dilution.  Why?  Dilute  i  part  of 
blood  to  20  parts  of  the  acid.  Why  ?  Use  same  counting  chamber 
as  for  red  cells  but  use  entire  field  of  i  or  ^  objective  as  area  to  be 
counted.  Adjust  draw  tube  till  the  field  is  a  circle  with  10  squares 
of  counting  chamber,  or  i^  of  a  millimeter,  for  its  diameter.  Then 
its  radius  will  be  2%  or  \  mm.,  and  the  area  of  the  field  to  be 
counted  is  the  area  of  the  circle. 

Formula  for  the  determination  of  number  of  white  corpuscles. 

Let  X  =  number  of  cells  per  cu.  mm. 

Let  Y  =  total  number  counted  in  given  number  of  fields  (N). 


64  LABORATORY    GUIDE    FOR    HISTOLOGY. 

Let  N  =  number  of  fields  counted  (usually  20  fields). 

Y 

'Then  -   =  average  number  of  corpuscles  per  field. 

yL  mm.  =  thickness  of  film.     Therefore,  average  number  of  corpuscles  in 

,        Y  .    . 

areas  counted,  or— ^  multiphed  by  10   ==  average  number  in  a  field  having  a 

thickness  of  one  millimeter. 

J^  =  dilution.     Therefore,  average  number  counted  multiplied  by  20   = 
actual  value. 

TT  times  square  of  radius  =  area  of  circle,  tt  =  3.1416. 

Y 

—  X  10  X  20 

Then,  ^ =X  or  ^1-02  Y  =  X. 

ttX   R2 

8.  Estimation  of  hemoglobin. 

The  Gow  hemoglobinometer  as  modified  by  Sahli  will   be  supplied. 

(a)  The  standard  color  tube  of  picrocarmin  solution  corresponds 
to  the  color  of  a  i  per  cent,  solution  of  normal  blood  in  distilled 
water.     Why  distilled? 

(b)  The  blood  is  drawn  in  the  capillary  tube  graduated  for  20  cubi; 
millimeters. 

(c)  The  graduated  test  tube  is  for  diluting  and  measuring  the  diluted 
blood. 

With  clean  medicine  dropper,  put  a  few  drops  of  distilled  water  in 
the  graduated  test  tube.  Draw  the  20  cu.  mm.  of  blood  and 
after  wiping  off  the  tip  of  the  pipette,  force  the  blood  into  the  water 
in  the  test  tube.  Wash  pipette  with  distilled  water  2  or  3  times,  forc- 
ing the  washings  into  the  test  tube.  Then,  drop  by  drop,  add  more 
distilled  water  to  mixture  in  test  tube  till  the  color  against  white  paper 
held  to  the  light  corresponds  to  the  color  of  the  standard  solution 
held  likewise.  Then  read.  If  the  reading  is  100  on  the  graduated 
test  tube,  then  the  amount  of  hemoglobin  is  normal.  If  above  or 
below,  the  percentage  above  or  below  normal  may  be  read. 

9.  Blood  formation. 

(a)  In  a  section  of  a  mammalian  embryo,  note  the  form  of  the  red 
corpuscles  in  the  blood-vessels  and  in  the  liver  or  spleen  of  the 
embryo.     Sketch  a  few  showing  their  character  and  variations. 

(b)  Red  bone  marrow.  Cut  off  the  sternal  end  of  a  rib  or  the  epiphysis 
of  one  of  the  long  bones  of  a  freshly  killed  animal  (dog);  with 
strong  forceps  squeeze  out  some  of  the  red  marrow  and  make  two 
cover-glass  smear  preparations  as  for  blood.  Fix  for  ^  to  2  hours 
in  ether-alcohol.  Transfer  to  95  per  cent,  alcohol,  then  to  70  per 
cent.  alc(jho],  then  to  water,  five  minutes  in    each,  and  stain   in 


BLOOD    FORMATION.  65 

hematoxylin  and  eosin  for  twenty  minutes.  Wash,  dehydrate  in 
alcohol,  clear  in  Xylol  and  mount  as  in  5  (e).  Look  for  nucleated 
erythroblasts,  normoblasts  and  ordinary  red  corpuscles.  Relative 
abundance  of  hemaglobin  ?  What  is  the  fate  of  the  nuclei  ?  Eosin- 
ophilic leukocytes?  Myelocytes  and  myeloplaxes?  Explain  the 
latter.  Evidences  of  cell  division?  Sketch  an  area  showing  a 
number  of  the  forms  of  red  cells  identified. 

The  spleen  and  lymph  glands  may  be  also  considered  in  con- 
nection with  blood  formation.  White  blood  corpuscles  are  especi- 
ally abundant  in  them  and  may  be  observed  in  the  process  of 
division. 

LITERATURE  ON  BLOOD. 
Development. 

ASCHHEIM,  S.  Zur  Kentniss  der  Erythrocytenbildung.     Arch.  f.  Mik.  Anat.,  Bd.  60,  H. 

2,  igo2. 
EHRLICH,  L.    Der  Ursprung  der  Plasmazellen.      Arch.  f.  pathol.  Anat.,  Bd.  175.  H.  2, 

p.  198,  1904. 
FUCHS,  H.  Ueber  die  sogenannte  "intracellulare"  Entstehung  der  roten  Blutkorperchen 

junger  und  erwachsener  Sauger.     Anat.  Hefte,  Bd.  22,  p.  95,  1903. 
HEINZ,  R.  Der  Uebergang  der  Embryonalen  KernhaUigen  roten  Blutkorperchen  in  Kern- 
lose  Erythrocyten.     .Arch.  f.  path.  Anat.,  Bd.  168,  p.  504,  1902. 
JOLLY,  J.  Recherches  experimentales  sur  la  division  indirecte  des  globules  rouges.     Arch. 

d'Anat.  Micros.,  T.  6,  Ease.  4,  p.  455,  1904. 
JOLLY,  J.  Recherches  sur  la  formation  des  globules  rouges  des  mammiferes.     Arch,  d' 

Anat.  Micros.,  T.  9,  Ease.  2,  p.  133,  1907. 
JOLLY,  M.  J.  Recherches  sur  la  di\-ision  indirect  des  cellules  lymphatiques  granuleuses  de 

la  moelle  des  Os.  Arch.  d'Anat.  Micros.,  T.  3,  p.  168,  1900. 
MALASSEZ,  L.  Sur  I'origine  et  la  formation  des  globules  rouges  dans  la  moelle  des  Os. 

Arch,  de  Physiol,  norm,  et  Path.,  Ser.  2,  T.  9,  p.  i,  1882. 
RETTERER,  E.  Des  Hematics  des  Mammiferes,  cie  leur  Development  et  de  leur  valeur 

cellulaire.     Jour,  de  I'Anat.  et  Physiol.,  T.  42,  No.  6,  p.  567,  1906. 
SEEMANN,  J.  Die  blutbildenden  Organe.     Ergebn.  d.  Physiol.,  Jg.  3,  Abt.  1,  Biocheniie, 

p.  I,  1904. 
WEIDENREICH,  F.  Studien  uber  das  Blut  und  die  blutbildenden  und-  zerstorenden  Organe. 

Arch.  f.  Mik.  Anat.,  Bd.  69,  H.  2,  p.  389,  1906. 
WILLIAMS,  E.  T.     The    Demonstration  of  Nucleated  Red   Blood-corpuscles  in   .\nimal 

Spleens.     Am   Med.,  Vol.  6,  p.  855,  1903. 
WILLIAMS,  E.  T.  Marrow  Cells  and  Spleen  Cells,  Considered  in  their  Relation  to  Blood 

Cells.     Am.  Med.,  Vol.  3,  p.  684,  1902. 
WRIGHT,  J.  H.  Die  Entstehung  der  Blutplattchen.     Virchow's  Arch.  f.  pathol.  Anat.,  Bd. 

186,  H.  I,  p.  55,  1906. 

General. 

.\LBRECHT,  E.  Die  Htille  der  roten  Blutkorperchen,  ihre  physiologische  und  pathologische 
Bedeutung.  Sitzungsber.  d.  Gesellsch.  f.  Morphol.  u.  Physiol,  in  Munchen,  Bd. 
19,  H.  2,  p.  16,  1903. 

BURKER,  H.  Blutplattchen  und  Blutgerinnung.  Munchen.  med.  Wochenschr.,Jg.  51,  No. 
27,  p.  1189,  1904. 

CESARIS-DEMEL,  A.  Studien  iiber  die  roten  Blutkorperchen  mit  den  Methoden  der  Far- 
bung   in  frischen  Zustande.     Folia  Hematol.,  Jg.   4,   Suppl.     No.   i,  p.   i,   1907. 

EWING,  J.,  and  STR.\USS,  I.  Precipitins  and  their  Medicolegal  Use.     Medical  News,  1903. 

FEDERICI,  F.  Un  nouvo  methodo  per  la  colorazione  delle  Mastazellen.  Anat.  Anz.,  Bd. 
29,  No.  13-14,  p.  357,  1906. 

FERRATA,  A.  Valeur  clinique  de  recherches  recentes  sur  les  globules  rouges.     Folia  Hema 
tol.,  Jg.  4,  Suppl.  No.  I,  p.  S3,  1907- 

GRUENBERG,  C.  Beitriige  zur  vergleichenden  Morphologic  der  Leukocyten.  \'irchow's 
.\rch.,  Bd.  162,  H.  2,  p.  303,  1901. 


66  LABORATORY    GUIDE    FOR   HISTOLOGY. 

GULLAND,  G.  L.  Classification,  Origin  and  Probable  Role  of  Leukocytes,  Mastcells  and 

Plasmacells.     Folia  Hematol.,  Jg.  3,  No.  lo-ii,  p.  637,  1906. 
HELBER,  E.  Ueber  die  Zahlung  der  Blutplattchen  im  Blut  des  Menschen  und  ihr  Verhalten 

bei  pathologischen  Zustanden.     Dtsch.  Arch.  f.  klin.  Med.,  Bd.  81,  H.  3-4,  p.  316, 

1904. 
LARRABEE,  R.  C.    The  Estimation  of  Luecocytes  from  Stained  Bloodsmears.     Jour,  of 

"Med.  Research,  Vol.  16,  No.  2,  p.  223,  1907. 
LEWIS,  F.  T.  The  Shape  of  Mammalian  Red  Blood-corpuscles.     Jour,  of  Medical  Research, 

Vol.  10,  No.  4,  1904. 
LOEHNER,  L.  Beitrage  zur  Frage  der  Erychrocytenmembran  nebst  einleitenden  Bemerkun- 

gen  liber  den  Membranbegriff.     Arch.  flir.  Mik.  Anat.,  Bd.  71,  H.  i,  p.  129,  1907. 
QUINAN,    C.  Ueber  specifische   Erythroh'se.     Beitrage   zur  chemischen   Physiologie   und 

Pathologie,  Bd.  5,  H.  3  and  4,  1904. 
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Pathol.  Soc.  Philadelphia,  n.s.  Vol.  9,  p.  139,  1906. 
RUZICKA,  V.  Beitrage  zur  K^nntnis  des  Baues  der  roten  Blutkorperchen.     Anat.  Anz., 

Bd.  23,  p.  298,  1903. 
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589,  1905. 
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Anat.,  Vol.  174,  p.  294,  1903. 
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Erythrocytes  of  Man.     Jour.  Med.  Research,  Vol.  10,  p.  342,  1903. 
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p.  152,  1906. 


III.  THE  MUSCULAR  TISSUES. 

(fifth  paper.) 

A.  Smooth  or  Non-striated  Muscle. 

1.  Remove  a  shred  of  one  of  the  muscle  layers  of  a  bladder  which  has 
been  fixed  in  2;}  per  cent,  alcohol.  With  needles  tease  it  apart  in  a  watch 
glass  of  the  alcohol,  and  then  replace  the  alcohol  with  enough  dilute 
Delafield's  hematoxylin  to  cover  the  tissue  and  let  the  stain  act  15  to 
20  minutes.  Wash  out  surplus  stain  with  70  per  cent,  alcohol,  and 
replace  70  per  cent,  with  a  few  drops  of  a  i  per  cent,  alcoholic  solution 
of  eosin  for  5  minutes.  Wash  out  eosin  with  95  per  cent,  alcohol  and 
replace  95  per  cent,  with  "clearing  oil."  After  clearing  10  minutes, 
transfer  a  small  shred  of  the  tissue  to  the  slide  and  carefully  tease  the 
muscle  "cells"  apart.  Drain  off  surplus  clearing  oil,  mount  in  balsam 
and  examine  under  high  power.  What  is  the  shape  of  the  muscle  cell  ? 
How  many  nuclei?  Their  shape  and  where  situated?  What  is  the 
structure  and  general  arrangement  of  the  cytoplasm?  What  is  the 
"anisotropic  substance?"  Is  there  any  difference  in  cytoplasmic 
structure  in  the  immediate  %dcinity  of  the  nuclei  ?  Is  there  a  cell  mem- 
brane ?     Intercellular  cement  ?     Draw  two  or  three  cells. 

2.  Study  a  thin  stained  section  of  the  tunica  muscularis  of  the  stomach 
or  intestine.  Wliat  differences  are  to  be  noted  between*  this  smooth 
muscle  cell  and  that  from  the  bladder?  Are  there  any  indications  of 
intercellular  bridges?  Make  a  careful  drawing  of  a  small  group  of 
cells  in  transverse  section,  illustrating  the  intimate  structure  of  the  cell  and 
intercellular  relations.  What  is  the  natural  shape  of  the  fiber  in  transverse 
section?  Also,  from  the  same  preparation,  make  a  careful  drawing 
of  a  cell  cut  longitudinally  showing  the  nucleus  and  its  immediate 
vicinity  and  the  muscle  fibrillEe.  Where  in  the  body  are  the  longest 
smooth  muscle  cells? 

B,  Striated  muscle. 

I.  Cardiac  muscle. 

(a)  Carefully  tease  a  small  shred  of  heart  muscle  which  has  been  sub- 
jected to  the  dissociating  action  of  o.i  per  cent,  chromic  acid.  In 
a  watch  glass,  stain  in  picrocarmin  2  to  24  hours,  wash  in  70 
per  cent,  alcohol,  dehydrate,  clear,  and  mount  in  balsam.  How 
does  this  "cell"  dift'er  from  those  previously  examined?  Position 
and  number  of  nuclei?     What  is  the  shape  of  the  cell  and  its 

67 


68  LABORATORY    GUIDE    FOR    HISTOLOGY. 

relation  to  other  cells  ?  Note  separated  muscle  fibrillae  (sarcostyles). 
Staining  character  of  the  intercellated  disks  or  lines  of  junction 
between  cells? 
(b)  From  a  specially  stained  (Kolossow's  method)  thin  section  of  heart 
muscle  make  a  drawing  of  i  or  2  cells  showing  their  shapes,  struc- 
ture, and  interrelations.  Note  carefully  the  arrangement  of  the 
anisotropic  substance  resulting  in  the  two  forms  of  striation. 
Cement  substance  between  fibers  and  cell  membranes?  Does  a 
branch  of  one  fiber  always  join  a  branch  of  another?  Structural 
characters  of  the  intercellated  disks  or  lines  of  junction  of  cells? 
Fibril  bundles,  their  arrangement  in  cross-section,  and  the  role  of 
Krause's  membrane  in  them?  Consider  the  peripheral  mem- 
branes, connecting  Krause's  membranes,  along  the  sides  of  the 
fibril  bundle,  as  a  sarcolemma  and  note  the  effect  of  such  a  consid- 
eration upon  the  conception  of  individual  cardiac  cells.  From 
the  studies  made  of  smooth  and  cardiac  muscle,  what  may  be  said 
of  evidences  that  the  original  syncytium,  from  which  they  are 
derived,  is  maintained  ? 

2.  Skeletal  or  ^^ voluntary^'  muscle. 

(a)  Fresh.  Remove  a  small  shred  of  an  extended  skeletal  muscle  of  a 
mammal  which  has  been  chloroformed  several  hours.  Tease 
finely  on  the  slide  in  a  drop  of  normal  salt,  cover  and  examine. 
What  is  the  color  of  the  tissue?  What  can  you  observe  as  to  the 
shape  and  appearances  of  a  single  muscle  fiber  ("cell")?  Now 
r|move  the  cover,  replace  the  salt  solution  with  a  drop  of  i  per  cent 
acetic  acid,  let  this  act  5  minutes,  remove  it  with  filter  paper,  and 
mount  in  glycerin.  Under  high  power  distinguish  the  more 
evident  anisotropic  elements  (fibrils  or  sarcostyles)  surrounded  by 
the  "isotropic"  substance  (sarcoplasm).  Number  of  nuclei  in 
each  fiber?  Where  are  the  nuclei  situated?  Look  for  demon- 
strations of  the  sarcolemma  where  fibers  have  been  compressed 
by  the  needles  in  teasing,  and  also  for  the  end  of  a  fiber.  Sketch  a 
short  segment  of  a  single  fiber.  What  is  the  sarcolemma  ?  Com- 
pare the  cell  with  a  syncytium.  Measure  the  diameter  of  10  fibers 
and  determine  their  average  thickness  in  micromillimeters.  What 
length  may  they  attain  ? 

(b)  Areas  of  Cohnheim.  For  comparison,  use  stained  transverse 
sections  of  striated  muscle  from  the  human  subject,  the  frog,  and 
an  insect  (hydrophilus).  From  each  of  these  (under  high  power) 
sketch  a' transverse  section  of  a  single  muscle  fiber  choosing  those 
with  the  most  apparent  grouping  of  the  sarcous  elements  or  fibrilkc 
(muscle  columns)  in  the  sarcoplasm.  What  is  the  relation  of  the 
components   of   these    areas  of  Cohnheim  to  the  transverse  and 


NERVE    SUPPLY    OF    MUSCLE.  69 

longitudinal  striation  of  the  fiber?  What  are  the  chief  differences 
to  be  noted  in  the  structure  of  the  muscle  from  the  three  specimens  ? 
What  is  the  most  probable  significance  of  the  areas  of  Cohnheim? 
Include  endomysium  and  sarcolemma  in  sketches.  Make  a 
low  power  sketch  illustrating' the  arrangement  of  all  the  muscle 
envelopes  from  epimysium  to  sarcolemma. 

(c)  Muscle  fibrillas  and  their  relations  to  the  striations.  From  thin 
longitudinal  sections  of  relaxed  (extended)  mammalian  muscle, 
sketch  a  few  fibrillse  showing  the  arrangement  of  the  anisotropic 
and  isotropic  substances  (fibrillas  and  sarcoplasm)  into  the  following 
four  bands  (disks  of  entire  fiber)  composing  a  "muscle  segment." 

(i)  The  large  transverse  anisotropic  disk,  (Brucke's  line)  divided 
by  the  more  narrow,  more  isotropic,  Hensen's  disk  (median  mem- 
brane of  Heidenhein). 

(2)  The  thicker,  isotropic  disks,  one  on  either  side  of  the  transverse 
anisotropic  disks. 

(3)  The  intermediate  disk  or  membrane  of  Krause,  separating  the 
isotropic  discs  and  forming  the  boundaries  between  adjoining 
segments. 

(The  accessory  disk  of  Englemann   and  the  resulting  terminal 
disk  of  Merkel  are  described  for  insect  muscle,  in  addition  to  the 
above  four.) 
In  case  of  contracted  muscles,  Hensen's  disk  does  not  show.    Why  ? 

(d)  The  blood  supply  of  muscle.  Remove  a  bit  of  injected  muscle 
which  has  been  preserved  in  alcohol  or  formahn,  dehydrate  in  95 
per  cent,  alcohol  5  minutes;  transfer  to  clearing  oil,  5  minutes;  tease 
on  the  slide  (not  too  finely)  and  mount  in  balsam.  Under  medium 
magnification  sketch  a  few  fibers  showing  the  distribution  of  the 
blood  capillaries  among  them.  How  is  the  muscle  nourished  directly, 
and  supplied  with  oxygen?^ 

(e)  The  relation  of  muscle  to  tendon.  From  a  longitudinal  section 
passing  through  the  line  of  junction  between  muscle  fibers  and 
tendon  fibers^  sketch  2  or  3  muscle  fibers  showing  the  nature  of 
their  insertion  and  attachment  to  the  tendon.  How  do  the  fibers 
end?  Significance  of  the  increased  number  of  nuclei?  Intimate 
character  of  the  attachment? 

(f)  The  nerve  supply  of  the  muscle.  From  a  preparation  of  mamma- 
lian muscle  stained  with  gold  chlorid  or  methylen  blue,  sketch 
a  motor-nerve  termination.  How  is  the  substance  of  the  muscle 
cell  modified  in  the  "end-plate?"  Note  branching  of  the  nerve 
fiber.  Look  for  sensory  nerve  termination  or  "neuromuscular 
spindles."  Their  difference  and  the  difference  of  the  muscle  fiber 
they  involve  ?  The  many  other  forms  of  nerve  terminations  will  be 
treated  under  the  "sense-organs." 


yo  LABORATORY    GUIDE    FOR    HISTOLOGY. 

LITERATURE  ON  THE  MUSCLE  TISSUES. 
Development. 

BARDEEN,   C.  R.  The  Development  of  the  Musculature  of  the  Body  Wall  in  the  Pig. 

Including  its  Histogenesis  and  its  Relations  to  the  Myotomes  and  to  the  Skeletal 

and  Nervous  Apparatus.     Johns  Hopkins  Hosp.  Reports,  Vol.  9,  1898. 
BRODMAN,  K.  Bemerkungen  iiber  die  Fibrillogenie  und  ihre  Beziehungen  zur  Myelogenic 

mit    besonderer    Beriicksichtigung   der    Cortex    cerebri.     Neurol.    Centralbl.,    Bd. 

1907,  No.  8. 
HARRISON,  R.  G.     An  Experimental  Study  of  the  Relation  of  the  Nervous  System  to  the 

Developing  Musculature  in  the   Embryo  of  the   Frog.     Am.  Jour.  Anat.,  Vol.  3, 

No.  2,  1904. 
MACCALLUM,  J.  B.  On  the  Histogenesis  of  the  Striated  Muscle-fibre,  and  the  Growth  of 

the  Human  Sartorius  Muscle.     Johns  Hopkins  Hosp.  Bui.,  No.  90-91,  1898. 
MARCEAU,  F.  Recherches  sur  la  structure  et  la  developpment  campares  des  fibres  cardiaques 

dans  la  serie  des  vertebres.     Ann.  des  Sc.  nat.,  Annee  79,  Ser.  8,  T.  19,  No.  5-6, 

241,  1904. 
SCHLATER,  G.  Histologische  Untersuchungen  iiber  das  Muskelgewebe.  2.     Die  Myofibrille 

des  embrj'Onalen  Hiihnerherzens.     Arch.  f.  mik.  Anat.,  Bd.  69,  H.  i,  p.  100,  1906. 
WILSON,  J.  G.  The  Relation  of  the  Motor  Endings  on  the  Muscle  of  the  Frog  to  Neighboring 

Structures.     Jour.  Comp.  Neurol,  and  Psychol.,  Vol.  14,  No.  i,  p.  i,  1904. 

Structure. 

BAETIGER,  W.  A.     A  Re\aew  of   Some  Recent  Work  on  the  Musculature  of  the  Heart. 

Bui.  Johns  Hopkins  Hosp.,  Vol.  17,  No.  181,  1906. 
BARFURTH,  D.  Ueber  Zellbriichen  glatter   Muskelfasern.     Arch,  f.  mik.  Anat.,  Bd.   38, 

p.  38,  1891. 
BAUM,  J.  Beitrage  zur  Kenntnis  der  Muskelspindeln.     Anat.  Hefte,  Bd.  13,  p.  249,  1900. 
BOHEMAN,  H.  Intercellularbrlicken  und  Saftraume  der  glatten  Muskelatur.  Anat.  Anz., 

Bd.  ID,  p.  305,  1895. 
CREVATIN,  F.  Ueber  Muskelspindeln  von  Saugetieren.     Anat.  Anz.,  Bd.  19,  p.  173,  1901. 
DOGIEL,  A.  S.    Die  Nervendigungen  im  Bauchfell,  in  den  Sehnen,  den   Muskelspindeln 

und  dem  centrum  tendineum  des  Diaphragma  beim  Menschen  und  Saugetieren. 

Arch.   f.    mik.  Anat.,  Bd.  59,  1901. 
EYCLESHYMER,  A.  C.  The  Cytoplasmic  and  Nuclear  Changes  in  the  Striated  Muscle  Cell 

of  Necturus.     Am.  Jour,  of  Anat.,  Vol.  3,  No.  3,  1904. 
FELIX,  W.  Die  Lange  der  Muskelfaser  bei  dem  Menschen  und  einigen  Saugethieren.     Fest- 
schrift fiir  Albert  von  Koelliker.     Wilhelm  Engelmann,  Leipzig,  1887. 
HEIDENHEIM,  M.  Ueber  die  Struktur  des  mehschlichen  Herzmuskelfaser.     Anat.  Anz., 

Bd.  20,  p.  ^^,  1901. 
OILMAN,  P.  K.    The  Effect  of  Fatigue  on  the  Nuclei  of  Voluntary  Muscle  Cells.     Am.  Jour. 

Anat.,  Vol.  2,  p.  227,  1902. 
GRABOWER,  Ueber  Nervenendigungen  im  menschlichen  Muskel.     Arch.  f.  mik.  Anat., 

Bd.  60,  p.  I,  1902. 
GODLEWSKI,  E.  Jr.,  Die  Entwicklung  der  Scelett-  und  Herzmuskelgewebes  des  Sauge- 

thiere.     Arch.  f.  mik.  Anat.,  Bd.  60,  H.  i,  1902. 
HEKTOEN,  L.  Segmentation  and  Fragmentation  of  the  Myocardium.     Am.  Jour,  of  Med. 

Sc,  November,  1897,  p.  i. 
HUBER,  G.  C.  Neuro-muscular  Spindles  in  the  Intercostal  Muscles  of  the  Cat.     Am.  Jour. 

Anat.,  Vol.  i,  1902. 
HUBER,  G.  C.     Note  on  the  Structure  of  the  Motor  Nerve  Endings  in  Voluntary  Muscle. 

Am.  Jour.  Anat.,  Vol.  i,  1902. 
KNAUT,  A.  Theorie  der  Protoplasma-  und  Muskelbewegung.     Arch,  f .  Entwicklungsmech. 

d.  Organ.,  Bd.  19,  H.  3,  p.  446,  1905. 
MUNCH,   K.  Ueber  Nucleinspiralen  im   Kern   der  glatten   Muskelzellen.     Arch.   f.   mik. 

Anat.,  Bd.  62,  p.  41,  1903. 
ODIER,  T.     Terminaison  des  nerfs  moteurs  dans  les  muscles  stries  de  I'homme.  Compt. 

rend.  Acad.  Sc,  T.  140,  No.  20,  p.  1361,  1904. 
PRENANT,  A.  Questions  relatives  aux  cellules  musculaires.    4.  La  substance  musculaire. 

Arch,  de  Zool.  exper.  et  gen.,  Ser.  4,  T.  2,  No.  7,  Notes  et  revue,  p.  113,  1904. 
RENAUT,  J.  Sur  les  disques  accessoires  de  la  zone  des  disques  minces  des  fibres  musculaires 

stries.     Compt.  rend.  Soc  Biol.,  T.  58,  No.  4,  p.  184,  1905. 
RENAUT etMOLLARD.  Le  Myocarde.     Revue  Generale  D'Histologie,  T.  i,  Fasc.  2, 1905. 
SCHAEFER,  E.  A.  The  Minute  Structure  of  the  Muscle  Fibril.     Anat.  Anz.,  Bd.  21,  p.  474, 

1902. 


IV.  THE  NERVOUS  TISSUES 

(sixth  paper.) 

The  Nerve  Cell  (cell-body  of  the  neurone). 

I.  External  Morphology. — From  sections  of  silver  (Golgi)  prepara- 
tions, make  drawings  accurately  illustrating  the  differences  in  shape, 
size,  and  detailed  contour  of  the  following  six  types  of  the  neurone : 

(a)  "Pyramidal   cell"   from   the   motor   gyri   of    the   celebral   cortex 
(human). 

(b)  Motor  cell  from  the  ventral  horn  of  the  human  spinal  cord. 

(c)  Typical  cell  from  the  spinal  ganglion. 

(d)  Purkinje's  cell  from  the  cerebellar  cortex. 

(e)  Either  a  "basket  cell"  or  a  "granule  cell"  from  the  cerebellum; 
and, 

(f)  A  cell-body  of  a  neurone  from  a  sympathetic  ganglion. 

(Silver  preparations  of  the  adult  spinal  ganglion  and  of  the  sym- 
pathetic neurone  are,  as  a  rule,  more  difficult  to  obtain  than  the 
other  varieties  mentioned.  The  human  or  pig  fetus,  or  the  rat  or 
rabbit  at  birth,  will  prove  more  fortunate  for  the  spinal  ganglion. 
The  more  difficult  method  of  the  so-called  "  intra vitam"  application 
of  methylen  blue  may  have  to  be  resorted  to  with  the  sympathetic 
ganghon,  and  this  method,  when  successful,  is  also  excellent  for 
demonstrating  the  external  morphology  of  the  spinal  ganghon 
neurone.  Cajal's  method  for  neurofibrillae,  often  results  quite  favor- 
ably with  both.) 

What  is  the  function  of  each  of  the  above  types?  How  do  they 
differ  as  to  the  abundance  and  arrangement  of  dendrites  ?  What 
are  the  gemmules  or  "pin-head  processes?"  In  what  does  the 
axone  differ  from  the  dendrites  ?  Localities,  peculiarities,  and  sig- 
nificance of  collaterals? 

2.  Internal  morphology  of  the  cell-body  of  the  neurone, 
(a)  From  a  transverse  section  of  the  cer\dcal  region  of  the  spinal  cord 
and  from  sections  of  a  spinal  gangUon,  both  of  which  have  been 
prepared  by  the  "Nissl-Held  method,"  make  a  careful  drawing 
of  one  of  the  larger  cells  of  the  ventral  horn  and  of  one  from  the 
spinal  ganghon.  Note  nucleus  and  nucleolus,  their  anatomy, 
position  and  size  as  compared  with  those  of  the  cells  of  other 
tissues.  Cell  membrane  and  cell  capsules?  The  occurrence, 
distribution,    and    significance    of    the    clumps    of    cliroviatophile 

71 


72  LABORATORY    GUIDE    FOR    HISTOLOGY. 

granules?  How  may  the  axone  be  distinguished  from  the  dendrites  ? 
Enumerate  the  differences  between  the  two  types  of  neurone. 
Note  the  general  shape  of  the  entire  section  of  the  spinal  cord  and 
that  of  the  areas  of  white  and  gray  substance.  What  is  the  relation 
and  connection  of  the  spinal  ganglion  to  the  spinal  cord  ? 
(b)  Study  the  "  neitro-fibrillcB"  in  a  large  ventral  horn  cell  or  pyramidal 
cell  stained  by  the  method  of  Cajal.  Their  extent,  distribution, 
and  significance?  Make  a  careful  drawing,  under  high  power, 
showing  them  in  their  relative  size  and  relation  to  the  cell  processes 
and  the  nucleus. 

3.  The  axone  or  nerve  fiber  (neuraxis  of  the  neurone). 

(a)  The  medullated  axone. 

(i)  Remove  a  piece  (5mm.  long)  of  one  of  the  spinal  nerves  of  the 
frog,  or  of  a  mammal,  and  tease  it  finely  on  the  slide  in  a  drop  of 
normal  salt.  (The  long  nerve  roots  lying  in  the  lumbo-sacral 
portion  of  the  vertebral  canal  are  best  for  teasing  in  that  the 
fibers  composing  them  are  less  invested  with  connective  tissue.) 
What  is  the  appearance  of  the  fresh  nerve?  Now  replace  the 
salt  solution  with  a  drop  of  i  per  cent,  osmic  acid  for  30  minutes. 
What  is  the  action  of  the  acid?  Wash  with  water,  mount  in 
glycerin,  and  examine.  What  is  the  structure  blackened  by 
the  osmic  acid?  Neurilemma?  Sheath  nuclei?  Nodes  of 
Ranvier?     Draw  a  segment  including  a  node. 

(2)  Silvered  nerve.  While  the  osmic  acid  is  acting  upon  preparation 
(i)  above,  remove  another  piece  of  spinal  nerve  from  the  animal, 
tease  it  slightly  on  the  slide  in  a  drop  of  i  per  cent,  silver  nitrate, 
then  place  it  in  a  corked  vial  containing  a  small  amount  of  this 
solution,  and  put  away  protected  from  light  for  from  one  to 
twelve  hours.  Then  tease  further  in  a  drop  of  glycerin  on  the  slide, 
mount  in  glycerin  and  expose  to  diffuse  sunlight  20  to  30  minutes. 
Under  high  power  draw  a  segment  of  a  nerve-fiber  showing  its 
general  appearance  and  the  "cross  of  Ranvier."  What  are 
the  components  of  the  cross?  To  what  appearance  in  (i)  does 
it  correspond?  What  part  of  the  fiber  constitutes  the  longer 
and  heavier  limbs  of  the  cross?  Fromman's  lines?  Neuri- 
lemma?    Nuclei?     Appearance  of  myelin  sheaths? 

(3)  Sections.  First,  from  a  paraffin  mount  containing  both  trans- 
verse and  longitudinal  sections  of  a  medullated  nerve  stained 
with  cosmic  acid  and  acid  fuchsin  (Kupffer's  method),  make 
drawings,  first  of  the  entire  transverse  section  under  low  power, 
showing  epineurium,  perineurium,  endoneurium,  sketching  in  a 
few  nerve-fibers  with  blackened  myelin  sheaths;  and  second,  draw 
one  or  two  fibers  under  high  power  showing  sheath,  neurilemma 


NERVE    TERMINATIONS.  73 

and  detailed  structure  of  the  axone.     What  is  the  neuroplasm? 
What  is  the  relation  of  the  axone  to  the  nerve-cell?     What  are 
the    segments   of   Lantermann   in   the    sheath?     Situation    and 
significance  of  sheath  nuclei?     Are  the  nerve-fibers  of  uniform 
size?     Measure   ten   in   transverse   section   and   determine   the 
average  diameters  of  both  sheaths  and  axones. 
Next,  from  sections  stained  by  the  Benda  neuroglia  method,  study  in 
detail  the  framework  of  the  myehn  sheaths.     Draw  a  transverse 
section  of  a   medullated  axone  and    also  a  small  portion  of   a 
longitudinal  section  including  the  region  of  a  node  of  Ranvier. 
Relation  of  the  neurilemma  and  sheath  nuclei  to  the  frame-work  ? 
Behavior  of  framework  in  the  formation  of  the  node?     Expla- 
nation of  Lantermann  segments? 
(b)  The  non-moduUated  axone  (Remak's  fibers).     Tease  a  piece  of 
sympathetic  nerve,  or  a  piece  of  the  vagus,  previously  treated  with 
cosmic    acid.     Observe    between    the    medullated    and    therefore 
blackened    fibers,    numerous    unblackened    fibers.     What    is    the 
nature   of   the   sheath   of   the   latter?     Are   there   sheath   nuclei? 
Nodes?     Are  there  any  indications  of  partial  medullation?     Do 
the  fibersever  branch?     Draw  several  sympathetic  fibers  showing 
varieties  and  characteristic  differences  from  the  medullated.     Non- 
meduUated  fibers  are  the  outgrowths  of  cell-bodies  situated  where  ? 

4.  Nerve  terminations. — Review  nerve  terminations  upon  muscle 
fibers,  and  Meissner's  (bulboid)  corpuscles  as  found  in  papillae 
corii  of  the  skin.  Draw  a  Pacinian  (lamellated)  corpuscle 
from  a  stained  preparation  made  from  the  mesentery  of  the  cat, 
and  compare  it  carefully  with  a  "Gential"  corpuscle  (demon- 
stration preparation).  What  is  the  general  difference  between  motor 
and  sensory  nerve  terminations?  Between  the  so-called  "free 
terminations"  and  the  encapsulated?  Compare  a  neurotendi- 
nous nerve  ending  (demonstration  preparation)  with  the  neuro- 
muscular variety.  What  is  the  behavior  of  the  medullary  sheath 
upon  the  approach  of  the  termination  of  the  axone  ? 
Nerve  terminations  will  be  further  studied  with  the  organs  of 
"special  sense." 

LITERATURE  ON  THE  NERVOUS  TISSUES. 

Cell-body  of  Neurone. 

APATHY,  S.     Das  leitende   Element   des   Nervensystems   und  seine   topographischen  Be- 

ziehungen  zu  den  Zellen.     Mitt.  a.  d.  Zool.     Station  zu  Neapel.  Bd.  12,  p.  495,  1S97. 
BEARD,  J.     The  Germ-cells,  Part  i.     (Contin.)     Jour,  of  Anat.  and  Physiol,  Vol.  38,  Pt. 

3,  p.  341,  1904-  ^ ,  .       , 

C.\JAL,  S.  R.     Variations  morphologiques  du  reticulum  neuronbnllaire  dans  certams  etats 

normaux  et  pathologiques.     Comt.  rend.  Soc.  Biol.,  T.  56,  No.  8,  p.  372,  1904. 
CAJAL,  S.  R.     Les  Metamorphoses  precoces  des  neurofibrilles  dans  la  regeneration  et  la 

degeneration  des  nerfs.     Travaux  up  Lab.     de  Rech.  biol.  de  I'Universite  de  Madrid. 

T.  5,  Ease.     1-2,  p.  47,  1907. 


74  LABORATORY    GUIDE    FOR    HISTOLOGY. 

CAMERON,  J.     The  Development  of  the  Vertebrate  Nerve-cell:    a  Cytological  Study  of 

the  Neuroblast-nucleus.     Brain,  Part  115,  p.  332,  1906. 
CIACCIO,  C.     Sur  de  reproduction  des  cellules  nerveuses.     Revue  Neurol.,  Oct.,  1906. 
COLLIN,  R.     Evolution  du  nucleole  dans  les  neuroblastes  de  la  moelle  epinure  chez  Tem- 

beyon  de  poulet.     Comp.,  rend,  de  1' Assoc,  des  Anat.,  8  Reunion,  Bordeaux,  p  .71, 

1906. 
FUCHS,  H.     Ueber  die  Spinalganglienzellen  und  Vorderhornganghenzellen  einiger  Sauger. 

^Anat.  Hefte,  H.  66,  (Bd.  21.  H.  i),  Erste  Abtheilung,  p.  97,  1903. 
GENTES  and  BELLOT.     Alterations  des  Neurofibrilles  des  cellules  de  I'ecorce  cerebrale 

du  chien,  aprez  ligature  de  la  carotide  primitive.         Compt.  rend.  Soc.  Biol.,  T. 

57,  No.  36,  p.  604,  1904. 
GUREWITSCH,  M.  J.     Ueber  die  Form  der  Nervenelemente  der  Kleinhirnrinde  verschied- 

ener  Vertebraten.     Neurol.  Centralbl.,  Jg.  24,  No.  2,  p.  54,  1905. 
HAMILTON,  A.     The  Division  of  Differentiated  Cells  in  the   Central  Nervous  System  of 

theWTiite  Rat.     Jour,  of  Comp.  Neurol.,     Vol.  11,  No.  4,  1901. 
HELD,  H.     Zur  Kenntnis  einer  neurofibrillaren  Continuitat  im    Centralnervensystem  der 

Wirbeltiere.     Arch.  f.  Anat.  u.  Physiol.,  Anat.  Abt.,  Jg.  1905,  H.  i,  p.  55  . 
HOLMGREN,    E.     Studien   in    der   feineren   Anatomic    der   Nervenzellen.     Anat.  Hefte, 

H.  47,  Abth.  I,  1900. 
JORIS,  H.     Des  neurofibrilles  et  de  leurs  rapports  avec  les  cellules  nerveuses.     BuU.  de 

I'Acad.  R.  de  Med.  de  Belgique.     p.  30,  1907. 
LEGENDRE,  R.     Sur  divers  aspects  de  neurofibrilles  intracellulaires  obtenus  par  la  methode 

de  Bielschowsky.     Anat.  Anz.,  Bd.  29,  No.  13,  14,  p.  361,  1906. 
LEWIS,  W.  H.     Experimental  Evidence  in  Support  of  the  Theory  of  Outgrowth  of  the  Axis 

Cyhnder.     Am.  Jour.  Anat.,  Vol.  6,  No.  4,  p.  461,  1907. 
MARINESCO,  G.     Recherches  sur  la  structure  de  la  partie  fibrillaire  des  cellules  nerveuses 

a    I'etat  normal  et  pathologique.     2.  Nouvelles  recherches  sur  les  neurofibrilles. 

Rev.  neurol.,  T.  12,  p.  405,  1904. 
MAYER,  S.     Wachstumsendkugeln  und  Ganglienzellen.     Anat.  Anz.,  Bd.  30,  No.  21,  p. 

536,  1907 

NEUFELD,  R.  P.  Ueber  ciie  Saftkanlachen  in  den  Ganglienzellen  des  Riickenmarks  und 
ihre  Beziehung  zum  pericellularen  Saftluckensysten.  Anat.  Anz.,  Bd.  23,  p.  424, 
1903. 

OLMER,  D.,  and  STEPHEN,  P.  Sur  le  developpment  des  neurofibrilles.  Compt.  rend. 
Soc.  Biol.,  T.  58,  No.  3,  p.  166,  1905  . 

ORZECHOWSKI,  K.  Ueber  Kernteilungen  in  den  Vorderhornzellen  des  Menschen.  Arb. 
a.  d.  Neurol.  Inst.     Wiener  Univ.,  Bd.  13,  p.  324,  1906. 

BATON,  S.  The  Histogenesis  of  the  Cellular  Elements  of  the  Cerebral  Cortex.  Contri- 
butions to  the  Science  of  Medicine  by  the  pupils  of  William  H.  Welch,  Baltimore, 
1900. 

BATON,  S.  A  study  of  the  Neurofibrils  in  the  Ganglion  Cells  of  the  Cerebral  Cortex. 
Jour.  Exper.  Med.,  Vol.  5,  p.  21,  1901. 

PRENTISS,  C.  W.  The  Neurofibrillar  Strpctures  in  the  GangUa  of  the  Leech  and  Cray- 
fish, With  Especial  Reference  to  the  Neurone  Theory.  Jour,  of  Comp.  Neurol., 
Vol,  13,  No.  3,  1903. 

ROHDE,  E.  Die  "Spharen"-Bildungen  der  Ganglienzellen.  Zool.  Anz.,  Bd.  28,  No.  10 
p.  359,  1904. 

Axone. 

BARBIERI,  N.  A.  Structure  des  nerfs  sectionnes  dans  une  evolution  strictement  physio 
logique.     Compt.  rend.  Acad.  Sc,  T.  144,  No.  24,  p.  1381,  1907. 

BOYCOTT,  A.  E.  On  the  Number  of  Nodes  of  Ran\-ierin  Different  Stages  of  the  Growth 
of  Nerve-fibres  in  the  Frog.     Jour,  of  Physiol.     Vol.  30,  No.  3-4,  p.  370,  1904. 

CAMERON,  J.  The  Histogenesis  of  Nerve-fibres:  A  Cytological  Study  of  the  Embryonic 
Cell  Nucleus.     Jour,  of  Anat.  and  Physiol.,  Vol.  41,  Pt.  i,  p.  8,  1906. 

CARLSON,  A.  J.,  and  JENKINS,  O.  P.  Physiological  Evidence  of  the  Fluidity  of  the 
Conducting  Substance  in  the  Pedal  Nerves  of  the  Slug — Ariolimax  columbianus. 
Jour,  of  Comp.  Neurol.,  Vol.  14,  No.  2,  1904. 

DOGIEL,  A.  S.  Zur  Frage  fiber  die  fibrillaren  Bau  der  Sehnenspindeln  oder  der  Golgischen 
Korperchen.     Arch,  fur  Mik.  Anat.,  Bd.  67,  H.  4,  p.  638,  1906. 

DONALDSON,  H.  H-  and  HOKE,  G.  W.  On  the  Areas  of  the  A.xis  Cylinder  and  Medul- 
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Comp.  Neurol,  and  Psychol.,  Vol.  15,  No.  i,  1905. 

FUCHS,  H.  Bemerkungen  fiber  den  Bau  der  Markscheide  am  Wirbeltiernerven.  Anat. 
Anz.,  Bd.  30,  No.  24,  p.  621,  1907. 


LITERATURE.  75 

VAN  GEHUCHTEN,  A.     Boutons  terminaux  et  reseau  pericellulaire.     Le  Xe\Taxe,  T.  6, 

Fasc.  2,  1904. 
HARDESTY,  I.     On  the  Occurrence  of  Sheath-cells  and  the  Nature  of  the  Axone  Sheaths 

in  the  Central  Nervous  System.     Am.  Jour.  Anat.,  Vol.  4,  No.  3,  p.  329,  1905. 
HARRISON,  R.  G.     Further  Experiments  on  the  Development  of  Peripheral  Nerves.     Am. 

Jour,  of  Anat.,  Vol.  5,  No.  2,  1906. 
HATAI,  S.     The   Neurokeratin   in   the   Medullary  Sheaths   of  the     Peripheral   Nerves  of 

Mammals.     Jour,  of  Comp.  Neurol.  Vol.  13,  No.  2,  1903. 
HELD,  H.     Zur  Histogenese  der  Nervenleitung.     Anat.  Anz.,  Suppl.  to  Bd.  29,  p.  185.  1906. 
HERRICK,  C.  J.     A  Note  on  the  Significance  of  the  Size  of  Nerve-fibres  in  Fishes.  Jour. 

Comp.  Neurol.,  Vol.  12,  No.  4,  1902. 
HUBER,  G.  C.     A  Contribution  on  the  nerve  Terminations  in  Neurotendinous  End-organs. 

Jour.  Comp.  Neurol.,  Vol.  10,  p.  159,  1900. 
KOELLIKER,  A.     Ueber  die  Entwickelung  der  Ner\'enfasern.     Anat.  Anz.,  Bd.  25,  No.  i, 

p.  I,  1904. 
KOLMER,  W.     Ueber  das  Verhalten  der  Neurofibrillen  an  den  Peripherie.     Anat.  Anz., 

Bd.  26,  No.  2C-2I,  p.  560,  1905. 
LEWIS,  W.  H.     Experimental  Evidence  in  Support  of  the  Outgrowth  Theory  of  the  Axis 

Cylinder.     Am.  Jour.  Anat.,  Vol.  6,  No.  4,  1907. 
MACDONALD,  J.  S.     Basophil  Granules  in  Nerve-fibres.      Jour,  of  Physiol.,  Vol.  32,  No. 

2  (Proc.  Physiol.  Soc),  1904. 
MAXWELL,  S.  S.     Is  the  Conduction  of  the  Nerve  Impulse  a  Chemical  or  a  Physical  Process  ? 

Jour,  of  Biol.  Chem.,  Vol.  3,  No.  5,  1907. 
NEUMANN,  E.     Aeltere  und  neuere  Lehren  liber  die  Regeneration  der  Nerven.     Virchow's 

Arch.  f.  pathol.  Anat.,  Bd.  189,  H.  2,  p.  209,  1907. 
SALA,  G.     Untersuchungen  uber  die  Structur  der  Pacini'schen  Korperchen.     Anat.  Anz., 

Bd.  16,  p,  193,  1899. 
SCHULZE,  O.     Zur  Histogenese  der  Peripheren  Ner^-en.     Anat.  Anz.,  Suppl.  to  Bd.  29,  p. 

179,  1906. 
THANHOFFER,    L.     Ueber   den    Ursprung    des    Achsencylinderfortsatzes    der   zentralen 

Nervenzellen.     Anat.  Anz.,  Bd.  26,  No.  ?2-23,  p.  623,  1905. 
TIMOFEEW,  A.     Ueber  die  Nervenendigungen  im   Bauchfelle  und  in  dem  Diaphragma 

der  Saugetiere.     Arch.  f.  mik.  Anat.,  H.  4,  Bd.  59,  p.  629,  1902. 
WLASSAK,  R.     Die  Herkunft  des  Myehns,   Arch.   f.   Entwicklungsmech.,   Bd.   6,  p.   453, 

1898. 
ZUCKERKANDL,  E.     Ueber  die  Collateralfurche.     Arb.  a.  d.  Neurol.     Inst.  a.  d.  Univ. 

Wien,  Bd.  11,  p.  407,  1904. 

Neurone  Theory. 

APATHY,  S.     Bemerkungen  zu  den  Ergebnissen  Ramon  y  Cajal  hinsichthch  der  feineren 

Beschaffenheit  des  Nervensystems.     Anat.  Anz.,  Bd.  31,  No.  17-18,  p.  481,  1907. 
BARKER,  L.  F.     The  Neurons.     Jour.  Am.  Med.  Assoc,  Vol.  46,  No.   13-14,  P-  929,  1906- 
DEJERINE,  J.     Quelques  considerations  sur  la  theorie  de  neurone.     Rev.  neurologique. 

No.  5,  p.  205,  1904. 
DOGIEL,   A.    S.     Ueber  die   Nervenendigungen  in  den   Grandryschen  und  Herbstschen 

Korperchen  im  Zusammenhange  mit  der  Frage  der  Neuronentheorie.     Anat.  Anz., 

Bd.  25,  No.  22,  p.  558,  1904. 
DOGIEL,  A.  S.     Der  fibrillare  Bau  der  Nervenendapparate  in  der  Haut  des  Menschen  und 

der  Saugetiere,  und  der  Neurontheorie.     Anat.  Anz.  Bd.  27,  No.  4-5.  1905. 
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5-6.  p.  231,  1905. 
GOLGI,  C.     La  Dottrina  del  Neurone — Teoria  e  Fatti.      Archivio  de  Fisiologia,  Vol.  4, 

Fasc.  3,  p.  187,  1907. 


MICROSCOPIC  ANATOMY  OR  ORGANOLOGY. 

I.     THE  CIRCULATORY  SYSTEM. 

(seventh  paper.) 

A.    The   Blood  Vascular  Apparatus. 
I.  The  blood-vessels. 
(a)  Arteries. 

(i)  From  a  stained  transverse  section  of  a  medium-sized  human 
artery  (femoral  or  carotid),  draw  in  detail  a  segment  showing 
the  various  tunics.  How  many  and  what  fundamental  tissues 
enter  into  the  structure  of  each?  How  many  cells  thick  is  the 
endothehal  lining  of  the  intima  ?  Note  carefully  the  elastic 
(fenestrated)  membranes  limiting  this  tunic.  Are  they  con- 
tinuous? What  can  be  said  as  to  the  extent  and  variety  of 
muscular  tissue  in  the  media  ?  Does  the  adventitia,  or  externa, 
permit  of  subdivision?  Compare  this  tunic  with  the  media. 
Note  vasce  vasorum. 

(2)  Draw  a  small  segment  from  a  stained  transverse  section  of  the 
aorta,  giving  special  attention  to  differences  between  its  structure 
and  that  of  the  medium-sized  artery. 

(3)  From  a  section  of  aorta  which  has  been  treated  with  a  special 
elastic-tissue  stain  (orcein,  for  example),  make  a  drawing  of  a 
small  segment  showing  the  relative  abundance  and  arrangement 
of  the  elastic  tissue  in  the  different  tunics. 

(4)  Fresh  tissue.  From  a  freshly  killed  mammal,  remove  a  small 
piece  of  a  medium-sized  artery  (femoral  or  carotid),  split  it 
longitudinally,  and  place  one  piece  in  r  per  cent,  silver  nitrate 
and  the  other  in  25  per  cent,  caustic  potash. 

(i)  After  the  first  piece  has  remained  about  25  minutes  in  the 
silver  nitrate,  transfer  it  to  a  slide  in  a  drop  of  glycerin,  scrape 
off  some  of  the  intima,  then  cover  the  whole  and  expose  to 
diffuse  sunlight.  When  the  silver  is  sufficiently  reduced, 
draw  a  small  area  under  high  power,  showing  the  relative  size, 
shape,  and  arrangement  of  the  endothelial  cells, 
(ii)  After  the  second  piece  of  artery  has  remained  in  the  caustic 
potash  for  one  to  two  hours,  lay  it  flat  on  the  slide,  and,  holding 
it  with  a  needle,  gently  scrape  both  sides  sufficiently  to  lay  bare 
from  both  sides  portions  of  a  "fenestrated  membrane." 
76 


THE    HEART.  77 

Cover  and  examine.     What  is  the  nature  of  the  membrane 
when  seen  on  the  flat  ?     Draw  a  small  area. 

(b)  Veins. 

(i)  From  a  stained  transverse  section  of  one  of  the  larger  veins, 
make  a  drawing  indicating  the  number  and  nature  of  its  tunics. 
Make  a  detailed  comparison  between  the  structure  of  the  vein 
and  that  of  the  artery. 

(2)  Compare  a  longitudinal  section  with  the  transverse.  Are  there 
any  differences  to  be  noted  in  the  appearance  of  the  tunics  as  cut 
in  the  two  planes  ?  Are  there  valves  ?  What  is  the  nature  of  the 
latter,  their  most  common  location,  and  whence  and  how  do 
they  originate  ? 

For  the  variations  in  the  structure  of  the  different  veins  and  the 
different  arteries  of  the  body,  see  the  text-books  and  the  liter- 
ature on  the  subject.  What  can  be  said,  in  general,  of  the  walls 
of  the  veins  below  the  heart  as  compared  with  those  above  it? 
Specific  structural  differences  between  the  vena  cava,  the  mesen- 
teric vein  and  the  jugular?  In  which  groups  of  veins  are  valves 
more  common,  and  in  which  are  they  probably  absent  ? 

(c)  Capillaries  and  pre-capillary  vessels. 

Place  a  small  sheet  of  mesentery  or  pia  mater  in  i  per  cent, 
silver  nitrate  for  one  to  twenty-four  hours.  Then  spread  flat  on 
the  slide,  mount  in  glycerin  and  expose  to  diffuse  sunlight  for  half 
an  hour  or  more.  What  is  the  structure  of  the  capillaries  ?  What 
modifications  have  taken  place  in  the  reduction  of  the  arteries 
and  veins  into  capillaries  ?  Draw,  showing  structure  and  a  branch- 
ing. xA.bundance  and  arrangement  of  muscle  ?  Then  draw  trans- 
verse sections  of  two  or  three  sizes  of  these  vessels  from  any  of  the 
stained  sections  showing  them.  May  arterioles  be  distinguished 
from  venules  ? 

2.  The  heart  (Cor)  (human  or  hog), 
(a)  External  features. 

(i)  The  pericardium,  the  visceral  portion  (epicardium)  and  the 
parietal  portion.  Where  do  the  two  portions  become  continu- 
ous?    What  fundamental  tissues  compose  the  pericardium? 

(2)  What  is  the  general  shape  of  the  heart?  Identify  right  atrium 
and  left  atrium  with  their  auriculae;  right  ventricle  and  left 
ventricle.  How  do  the  chambers  of  the  two  sides  difl'er  in  exter- 
nal features?  Identify  the  coronary  sulcus  (auriculo-ventric- 
ular  ring)  and  the  interventricular  sulcus. 

(3)  Vessels.  Superior  and  inferior  vena?  cavie  and  tlie  aorta.  Rela- 
tive   positions    and    physical    dift'erences?     Pulmonary    artery 


LABORATORY    GUIDE    FOR    HISTOLOGY. 

and  pulmonary  veins.  With  probe  determine  with  what  atrium 
or  ventricle  each  communicates.  Nature  of  the  blood  they 
carry  ?     Identity  the  superficial  coronary  vessels. 

(b)  Internal  features. 

There  are  several  procedures  for  making  the  incisions  of  the  heart 
for  study  and  for  autopsies.  The  following  procedure  is  excel- 
lent from  the  fact  that  it  allows  examination  of  all  the  important 
structures  and,  at  the  same  time,  the  parts  remain  connected 
and  easily  return  to  their  original  positions  for  purposes  of  orien- 
tation, 
(i)  Hold  heart  with  right  and  left  side  as  they  are  in  the  body 
and,  with  scissors,  make  the  following  incisions: 

Right  Side: 

(i)  Join  the  venae  cavae,  cutting  from  orifice  of  superior  to  that  of 

inferior, 
(ii)   Cut  down  right  border  of  heart  between  cusps  of  tricuspid 

valve  to  end  of  right   ventricle  (does  not  reach  apex), 
(iii)  Begin  a  little  above  end  of  the  last  incision  (to  save  anterior 

papillary  muscle)   and   pass    to    and  up  the  interventricular 

septum  to  the  pulmonary  artery. 


Lejt  Side: 


(i)   Join    pulmonary  veins  (4  orifices)  and  extend  cut  into   left 

auricle, 
(ii)  Thence,    between    bicuspid   valve    (mitral   valve),    along   left 

border  (middle  of  the  external  wall  of  left  ventricle)  to  apex, 
(iii)  P>om  termination  of  last  incision,  upwards  close  to  interven- 
tricular septum,  to  the  aorta,  avoiding  cutting   the  semilunar 
valve.     To  avoid  this  it   may  be   necessary  to  dissect  away 
some  of  the  pulmonary  artery  from  the  aorta. 
(2)  Having  completed  the  incisions,  identify  the  following  structures: 
(i)  Right  atrium:  sinus  venosus,  right  auricle,  septum  auricularum, 
orifice  of  vena  cava  with  its  Eustachian  valve,  coronary  sinus 
with  its  orifice,  fovea  ovalis  (with  foramen  ovalis?),  pectinate 
muscles  and  crista  terminalis. 
(ii)  Right  ventricle:  tricuspid  valve  with  anterior,  posterior  and 
medial   cusps;    orifice   of   pulmonary   artery   with   its   valve; 
papillary  muscles,  and  chordae  tendineae.     Does  the  muscular 
wall  vary  in  thickness? 
(iii)  Left  atrium:  left  auricle,  orifices  of  veins,  etc.     Which  veins? 
Differences  from  right  atrium  ? 


SECTIONS    OF    THE    HEART.  79 

(iv)  Left  ventricle:  bicuspid  valve  (mitral  valve)  with  its  anterior 
(aortic)  and  posterior  cusps;  semilunar  valve  with  its  three 
cusps  and  the  sinus  aortse  (valsalvae);  the  coronary  arteries, 
papillary  muscles,  trabeculce  carnai,  etc 

Make  a  sketch  showing  the  internal  structures  of  one  side  of 
the  heart. 

(c)  Dissection  of  muscular  walls.  By  pulling  apart  and  teasing  a 
heart  (fetal  pig)  which  has  been  macerated  in  strong  nitric  acid, 
verify  the  following  statements: 

(i)  The  heart  is  composed  very  largely  of  muscular  tissue  which  is 
arranged  in  layers. 

(2)  The  atria  consist  of  a  superficial  set  of  muscle-fibers  common 
to  both,  and  of  a  deeper  set,  proper  to  each. 

(3)  The  ventricles  consist  of  several  layers  of  muscle  forming  the 
myocardium.  Nearly  all  of  these  layers  begin  in  the  auriculo- 
ventricular  ring  of  one  ventricle  and  terminate  in  the  papillary 
muscles  of  the  other;  i.e.,  those  which  begin  near  the  outside 
of  one  ventricle  end  near  the  inside  of  the  other. 

(4)  The  thin  superficial  muscles  removed,  the  left  ventricle  is  formed 
of  scroll-like,  flat  bands  of  muscle,  continuous  with  the  muscle 
bands  which  cross  over  in  the  suptum  from  the  right  ventricle. 
Therefore,  taking  the  layers  together,  the  ventricles  consist 
chiefly  of  interfitting,  scroll-shaped  bands  of  muscle  with  tendons 
at  each  end.  Determine  the  existence  and  position  of  a  bundle 
which  belongs  exclusively  to  the  left  ventricle. 

What  is  the  position,  size,  shape  and  physiological  significance 
of  the  atrio-ventricular  bundle  ("Bundle  of  His")  ?  Does  the 
heart  possess  skeletal  structures? 

(d)  Sections. 

(i)  From  a  stained  transverse  section  through  the  ventricular  wall  of 
the  heart  (human)  make  a  drawing  showing  its  three  layers 
analogous  to  the  tunics  of  a  blood-vessel.  What  is  the  nature  of 
the  epicardium  ?  The  sublayers  of  the  endocardium  ?  Can  the 
myocardium  be  sub-divided  into  the  component  bands  above 
mentioned  ? 

(2)  From  a  longitudinal  section  through  the  left  atrium  and  mitral 
valve,  determine  the  origin  of  the  valve  segments.  On  which 
side  of  the  segments  is  fibrous  connective  tissue  most  abundant  ? 
Origin  and  arrangement  of  the  muscles  of  the  valve?  Draw 
and  indicate. 

(3)  Blood-supply  of  the  heart.  From  a  section  of  an  injected  heart 
draw  a  small  area  showing  the  arrangement  of  the  intrinsic  blood- 
vessels.    What  can  be  said  of  the  abundance  of  the  blood-supply? 


LABORATORY    GUIDE    FOR   HISTOLOGY. 

B.  The  Lymphatic  System. 

1.  Lymph-vessels. 

(a)  Make  a  careful  drawing  of  a  stained  transverse  section  of  the 
thoracic  duct.  Of  the  vessels  previously  studied,  which  does  it 
most  resemble  in  structure? 

(b)  From  a  section  of  the  intestine,  for  example,  draw  under  high 
power  a  small  area  of  the  mucosa,  showing  lymph  capillaries  and 
lymph-spaces.  What  can  be  said  as  to  their  lining  and  the  thick- 
ness of  their  walls?  What  other  and  larger  cavities  of  the  body 
may  be  classed  as  lymph-spaces? 

(c)  From  a  preparation  in  which  the  lymphatics  have  been  injected, 
draw  a  small  vessel  showing  its  characteristic  contour,  thinness  of 
wall,  and  evidence  of  frequent  valves.  Has  it  an  epithelial  lining? 
Differences  from  blood  capillaries  ? 

2.  Lymph-glands  (lymph  nodes). 

(a)  Fresh.  Observe  the  groups  of  lymph-glands  in  the  neck,  axilla  or 
groin  and  the  scattered  lymph-glands  in  the  mesentery  of  a  dog  or 
cat.  What  can  be  said  as  to  their  color,  size  and  shape?  Cut  a 
gland,  scrape  out  some  of  its  tissue,  mount  in  salt  solution  and 
examine  under  high  power.  What  is  the  shape  and  general 
character  of  the  cells? 

(b)  Make  a  sketch  of  an  injected  and  stained  sagittal  section  of  one  of 
the  medium  sized  lymph -glands  (dog  or  cat).  What  is  the  general 
shape  of  the  gland?  Note  the  connective  tissue  capsule  with  its 
ingrowths  or  trabecules  which  separate  the  cortex  of  the  gland  into 
corticle  follicles.  How  do  the  follicles  differ  from  the  medullary 
substance?  What  can  be  said  of  the  blood-supply  and  the  relation 
of  the  blood  capillaries  to  the  lymph  sinuses?  Under  high  power 
draw  an  area  from  the  center  of  a  follicle  or  nodule.  How  do  the 
cells  of  the  germ  center  differ  from  other  cells  of  the  follicle  ?  Cell 
divisions?  What  is  the  variety  of  the  connective  tissue?  Occur- 
rence of  blood  sinuses? 

(c)  'Lymph-nodules,  solitary  and  agminated,  will  be  best  considered  in 
connection  with  the  alimentary  tract. 

3.  Hemolymph-glands. 

(a)  What  is  the  distinctive  appearance  of  these  bodies  in  the  fresh  con- 
dition and  where  are  they  found  in  man  ?  Average  size  as  com- 
pared with  the  ordinary  lymph-glands? 

(b)  Draw  a  stained  sagittal  section  of  a  hemolymph-gland  (sheep  or 
human)  showing  the  structure  and  arrangement  of  the  capsule, 
the  thickness  and  extent  of  the  peripheral  blood  sinus  with  the 
reticular  connective  tissue  and  the  variety  of  cells  contained  in  it. 


GLANDS  WITH  INTERNAL  SECRETION.  8 1 

and  the  structure  of  the  medullary  portion  of  the  gland.  What  is 
the  relation  of  the  lymph-vascular  system  to  the  blood-vascular 
system  of  this  gland  as  compared  with  those  of  the  ordinary  lymph- 
gland?  Compare  \Yith  descriptions  of  marrow  lymph-glands. 
Review  bone  marrow,  considering  it  as  an  organ  of  the  lymphatic 
system.  Discuss  the  lymph-glands  as  both  mechanical  and  chem- 
ical filters  interposed  in  the  circulation. 

4.  The  spleen  (Lien). 

(a)  Fresh  (dog).  What  is  the  position,  color  and  shape  of  the  spleen? 
Where  do  the  vessels  enter  it?  With  a  sharp  scalpel  cut  out  a 
wedge  and  examine  it  in  salt  solution  under  the  dissecting  micro- 
scope. Carefully  observe  both  the  outer  surface  and  the  cut 
surface,  and  make  small  sketches  illustrating  both.  What  are  the 
small,  Hghter  spots  in  the  cut  surface?  Scrape  out  some  of  the 
tissue,  mount  in  salt  solution  and  examine  under  high  power. 
What  different  cells  can  be  observed?  Carefully  note  the  contents 
of  a  large  splenic  cell.  Compare  the  cells  with  those  of  the  ordinary 
lymph-gland. 

(b)  From  a  stained  vertical  section  of  the  spleen,  make  a  detailed 
drawing  of  the  spleen  lobitle,  including  the  capsule  of  the  spleen,  the 
interlobular  traheculcR,  and  the  intralohular  trabeculce.  Compare 
the  jnalpighian  corpuscle  and  the  germ  center  with  the  follicular 
nodule  of  the  lymph -gland.  How  do  the  cells  of  the  corpuscle 
differ  from  those  of  the  spleen  pulp  ?  What  are  the  spleen  cords  ? 
Note  the  intralobular  venous  spaces.  Examine,  under  high  power, 
for  the  fine  framework  of  reticular  connective  tissue.  In  the 
spleen  pulp,  look  for  the  various  t_\qDes  of  leukocytes  and  for  indi- 
cations of  the  development  of  red  blood-corpuscles.  Draw,  under 
high  power,  examples  of  four  varieties  of  the  cells  contained  in  the 
spleen.  Nature  of  the  inclusions  of  some  of  the  large  splenic  cells 
and  the  function  of  the  spleen  indicated  by  them? 

(c)  Blood-supply.  From  a  section  of  injected  spleen,  make  a  drawing 
showing  the  afferent  and  efferent  blood-vessels  of  a  lobule.  How 
does  the  artery  enter  the  spleen?  How  is  it  disposed  within  the 
lobule?  Look  for  ampullce  oj  Thoma.  How  do  the  veins  arise? 
How  does  the  arterial  blood  pass  into  the  venous  system?  What 
is  the  relation  of  the  inter-  and  intralobular  veins  to  the  trabe- 
culas?     Number  of  trabecular  concerned  in  each  lobule? 

C.  Glands  with  Internal  Secretion  (the  ductless  glands). 

The  lymph-glands  and  the  spleen  are  frequently  classed  as  ''ductless 
glands,"  though  neither  in  their  general  architecture  nor  in  their  ele- 
mentary details  may  they  be  considered  to  present  any  of  the  features 


LABORATORY    GUIDE    FOR    HISTOLOGY. 

characteristic  of  true  glandular  structure.  On  the  basis  of  function, 
also,  the  definition  of  "gland  with  internal  secr-etion"  might  be  strained 
sufficiently  to  include  them,  for  not  only  do  both  the  lymph-glands  and 
the  spleen  receive  and  act  upon  substances  from  the  blood,  but  they 
also  contribute  substances  to  the  blood,  modified  plasma  (lymph), 
white  blood-corpuscles,  and,  at  times,  the  spleen  and  marrow  contribute 
red  blood-corpuscles.  However,  upon  the  basis  of  their  structure,  and 
the  fact  of  their  being  directly  interposed  (as  nodes)  in  the  lymph  chan- 
nels, both,  the  lymph-glands  especially,  are  more  appropriately  studied 
as  intimate  parts  of  the  lymphatic  system  proper.  The  structures  more 
particularly  classed  as  "glands  with  internal  secretion"  are  those  which 
follow.  They  are  arranged  for  study  in  the  order  in  which  they  differ  in 
structure  from  the  so-called  lymph-glands. 

1.  The  thymus. 

(a)  From  texts  and  atlases  and,  if  possible,  in  a  human  fetus  or  infant, 
determine  the  position,  attachments,  shape,  size,  and  color  of  the 
thymus.  Note  its  very  evident  lobation  and  its  consistency.  Be- 
come familiar  with  its  origin  and  development  and  with  its  variable 
occurrence  and  persistence  at  different  ages.  At  what  age  is  it 
usually  largest  and  at  what  age  is  its  atrophy  usually  completed  ? 

(b)  From  a  stained  section,  sketch  a  lobule  showing  its  detailed  struc- 
ture, its  relation  to  other  lobules,  and  the  nature  of  the  interlobular 
tissue.  What  functions  may  be  inferred  from  its  structure  and  in 
what  does  it  differ  from  an  ordinary  lymph-gland?  Under  high 
power  draw  one  of  the  thymic  (Hassall's)  corpuscles  with  its 
immediate  surroundings.  Wliere  are  these  situated  and  at  what 
age  are  they  most  abundant  ?     Their  origin  and  significance  ? 

2.  The  glomus  caroticum  (the  " intercarotid  gland".) 

(a)  Learn  its  situation,  size  and  color  in  man.  From  a  stained  section 
draw  a  small  area  under  medium  magnification,  showing  its  struc- 
ture. What  is  its  origin  and  probable  function  ?  What  structures 
of  the  pancreas  does  it  resemble  and  in  what  features?  Read  up 
the  "cocygeal  glands^'  and  compare. 

3.  The  hypophysis  cerebri  (pituitary  body). 

(a)  From  models  and  atlases  and  from  a  demonstration  specimen  of 
the  brain  itself,  determine  the  position,  connections,  shape,  and 
orientation  of  the  hypophysis.  Its  size  and  color  in  the  fresh? 
What  are  the  conditions  under  which  it  has  been  found  to  vary  ? 

(b)  Draw  under  low  power  an  entire  stained  vertical  section  passing 
transversary  through  the  long  axis  of  the  body,  and  thus  in  the 
direction  of  its  infundibulum  and  involving  both  its  posterior  and 


THE    THYREOID    GLAND.  83 

anterior  lobes.  Show  carefully  the  difference  in  structure  between 
the  two  lobes.  Which  lobe  is  the  larger?  What  is  the  difference 
in  their  origin,  and  therefore,  which  is  directly  continuous  with  the 
infundibulum?  What  is  the  structure  of  the  latter  and  what  is  its 
relation  to  the  tuber  cinereum  and  third  ventricle  of  the  cerebrum  ? 
Which  of  the  two  lobes  is  most  concerned  in  the  enlargement  of  the 
hypophysis  accompanying  acromegaly  and  gigantism?  Look  for 
vesicles  (follicles)  containing  colloid  substance.  In  which  border 
of  the  lobe  containing  them  are  such  more  usually  found?  What 
can  be  said  of  the  nerves  of  the  two  lobes? 
(c)  Under  high  power,  draw  a  small  area  presenting  the  typical  structure 
of  the  anterior  (glandular)  lobe,  showing  the  branched  epithelial 
cords,  the  arrangement,  character,  and  the  varieties  of  the  cells,  and 
the  abundance  and  sinusoidal  character  of  the  capillaries.  Com- 
pare the  general  structure  of  this  lobe  with  that  of  the  parathyreoids 
below^ 

4.  The  thyreoid  gland. 

(a)  Determine  the  position,  shape,  and  lobes  of  the  human  thyreoid 
from  models,  texts  and  atlases.  How  is  it  attached  and  with 
which  laryngeal  and  tracheal  cartilages  is  it  most  intimately  asso- 
ciated? Examine  the  fresh  thyreoid  of  the  dog,  noting  its  color, 
consistency  to  touch  and  its  comparative  position.  Make  an  incision 
and  note  the  peculiar  character  of  the  exudate.  Review  the  origin 
of  the  thyreoid  gland  and  the  occurrence  of  vestiges  of  its  duct. 
What  can  be  said  of  the  thyreo-glossal  duct  of  man?  What  phe- 
nomena are  accepted  as  resulting  from  the  arrested  development, 
the  atrophy  and  the  enlargement  of  the  thyreoid  ? 

(b)  From  a  stained  section  of  a  lobe  (human),  draw  one  or  two  vesicles 
(follicles),  showing  the  nature  of  their  epithelial  lining,  and  the 
"colloid  substance"  enclosed,  and  the  intervening  connective 
tissue  and  blood-vessels.  What  varieties  of  epithelial  cells  are 
noticeable?  What  is  the  general  shape  of  the  vesicles?  Their 
variations  in  size  and  contents?  Cells  in  the  colloid  substance? 
Abundance  and  peculiar  character  of  the  blood-supply?  What  is 
the  intimate  relation  between  the  vesicles  and  the  blood  capillaries 
and  lymphatics? 

(c)  The  Parathyreoid  "glands."  State  the  position,  relation  to  the 
thyreoid,  variable  occurrence,  and  functional  significance  of  these 
structures.  Difference  in  color  from  the  thyreoid  ?  Draw  an  area 
from  a  stained  section  of  one  of  them,  showing  the  branched  epithe- 
lial cords,  the  two  varieties  of  cells  composing  them,  and  the  sup- 
porting tissue.  Occurrence  of  vesicles?  Is  colloid  substance  ever 
found?     Compare  with  structure  of  hypophysis. 


84  LABORATORY    GUIDE    FOR    HISTOLOGY. 

5.  The  suprarenal  glands  {Adrenals). 

(a)  From  models,  texts  and  the  human  cadaver,  determine  the  normal 
position  of  the  suprarenals,  their  relations  to  the  kidneys,  their 
shape,  size  and  their  peculiar  color  in  the  fresh.  Which  is  usually 
the  larger  of  the  two?  Why  did  the  older  anatomists  call  them 
"suprarenal  capsules?"  How  do  those  of  the  dog  differ  in  shape 
and  position  from  the  human?  Enumerate  the  arterial  branches 
supplying  the  suprarenals.     Nature  of  the  nerve-supply  ? 

(b)  From  a  stained  section  taken  vertical  to  the  surface  of  a  suprarenal 
gland  (human,  monkey  or  dog),  draw  a  narrow  strip  passing  from 
periphery  to  center,  illustrating  cortex  and  medulla,  and  showing 
in  detail  the  fibrous  capsule  (two  layers?),  the  zona  glomerulosa, 
zona  fasciculata,  and  zona  reticularis.  Note  carefully  the  differ- 
ences in  the  structure  and  staining  properties  of  the  cells  of  the 
different  zones.  What  is  the  significance  of  the  occasional  isolated 
clumps  of  cells  situated  among  the  cell-cords  of  the  medulla  but 
having  the  stain  reaction  of  the  zona  fasciculata  ?  Origin  of  the 
different  zones? 

(c)  Add  to  the  above  drawing,  opposite  each  locality,  careful  drawings 
under  high  power  of  two  or  three  cells  of  that  locality,  giving  special 
attention  to  cell  structures  and  staining  differences.  Which  cells 
contain  oil  globules?  Give  an  explanation  of  the  fact  that  the 
medullary  substance  is  differentially  colored  by  chromic  acid  and  its 
salts. 

(d)  Blood-supply.  From  a  thick  section  of  an  injected  specimen,  make 
an  illustration  of  the  distribution  of  the  capsular,  cortical  and 
medullary  arteries.  Where  are  the  venous  capillaries  situated? 
What  is  the  significance  of  the  similarly  derived  but  separate  blood- 
supply  of  the  cortical  and  medullary  substances?  What  is  the 
nature  of  the  walls  of  the  suprarenal  blood-vessels?  Explain  the 
arrangement  of  the  cells  into  cords. 

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88  LABORATORY    GUIDE    FOR   HISTOLOGY. 

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II.  THE  DIGESTIVE  APPARATUS. 

(eighth  paper.) 
A.  The  Mouth  Cavity  {cavtim  oris). 

1.  The  Ups. 

(a)  With  a  mirror  examine  the  lips  and  describe  the  differences  to  be 
noticed  in  the  transition  of  epidermis  proper  into  oral  mucous 
membrane.  Is  there  a  sharp  hne  marking  the  division  between 
the  two  ?     Explain  the  differences  in  color  and  evenness  of  surface. 

(b)  From  a  vertical  transverse  section  of  the  labium  inferus  make  a 
drawing  illustrating  the  following  features:  (i)  the  variations  in  the 
epithelium  in  the  transition  of  epidermis  into  oral  mucous  mem- 
brane; (2)  the  variations  in  the  height  of  the  papillae  corii;  (3)  the 
relative  abundance  of  the  tela  subcutanea  and  the  tela,  submucosa, 
and  the  presence  of  glandulae  sebaceae  and  sudoriferae  in  the  one 
and  glandulae  labiales  in  the  other.  What  constitutes  the  tunica 
propria  in  the  one  and  the  tunica  mucosa  in  the  other?  (4)  vertical 
muscle-fibers  (M.  depressor  septi)  and  horizontal  muscle-fibers 
(M.  orbicularis  oris).  Variety  of  muscle?  In  the  papillae  of  the 
submucosa,  look  for  corpuscles  of  Krause  (corpuscula  bulboidea). 
What  can  be  said  of  the  relative  abundance  of  the  tela  subcutanea 
on  the  back  of  the  hand,  of  the  lip,  of  the  hard  palate  and  of  the 
tongue  ? 

2.  The  tongue  (lingua). 

■  (a)  With  the  aid  of  a  mirror  and  magnifying  glass  sketch  the  dorsal 
surface  of  the  tongue,  paying  special  attention  to  the  following 
features:  (i)  the  apex  and  the  sulcus  medianus  linguae;  (2)  the 
tonsillae  linguales  and  the  sulcus  terminalis  linguae;  (3)  the  arrange- 
ment number,  shape  and  size  of  the  papillae  vallata.^;  (4)  the  size  and 
distribution  of  the  papillae  fungiformes,  and  (5)  the  appearance 
and  position  of  the  papillae  folliatae,  papillae  conica?,  and  papillae 
filiformes. 

(b)  Hold  the  tongue  up  as  high  as  possible,  and  sketch  the  following 
features  on  its  ventral  aspect:  (i)  apex  and  frenulum  linguae;  (2) 
plicae  fimbriatae;  (3)  vanine  veins  (venae  sublinguals);  (4)  plicae 
sublinguales  and  carunculae  sublinguales  with  orifices  of  (Wharton's) 
ducts  of  submaxillary  glands,  and  bulges  of  the  mucous  membrane 
indicating  the  position  of  the  glandulce  sublinguales. 

(c)  From  vertical  sections  taken  from  various  regions  of  the  dorsal 

89 


9©  LABORATORY    GUIDE    FOR    HISTOLOGY. 

surface  make  drawings  illustrating  the  shape,  structure  and  relative 
size  of  five  forms  of  lingual  papillae.  How  are  they  formed? 
What  is  their  relation  to  the  papillce  of  the  submucosa?  Let  one  of 
the  drawings  include  such  lingual  muscles  as  the  section  may  con- 
tain and  attach  the  names  of  the  muscles  identified.  In  which 
papillae  are  situated  the  specialized  corpuscles  of  the  sense  of  taste  ? 
From  the  papilla;  foUiatas  of  the  rabbit  make  a  detailed  drawing  of 
a  taste-bud  (calyculus  gustatorius). 

3.  The  soft  palate  {palatimim  molle). 

(a)  With  mirror  observe  the  shape,  position  and  faciUty  of  movement 
of  the  soft  palate.  Make  a  sketch  showing  the  uvula  palatina, 
tonsilae  palatina;,  the  fossae  supratonsilares,  and  the  arcus  glosso- 
palatinus. 

(b)  Draw  a  vertical  median  section  of  the  uvula  showing  the  kind  of 
papillae,  the  glandulas  palatinas  and  their  ducts,  the  vertical  M.  uvulae 
and  oblique  fibers  of  the  M.  levator  vefi  palatini.  Variations  of  the 
epithelium  of  the  two  sides?     Position  and  variety  of  the  glands? 

4.  The  glands  of  the  mouth  (glandulce  oris). 

(a)  The  small  glands.  Examine  the  glandulas  labiales,  linguales  and 
palatinae  in  the  sections  studied  in  i  (b),  2  (c)  and  3  (b).  What 
differences  are  to  be  noted  as  to  the  size  and  staining  properties 
of  the  cells  of  the  various  glands?  Draw  under  high  power  a 
transverse  section  of  a  duct  and  one  or  two  alveoli  from  both  a 
mucous  and  a  serous  gland,  illustrating  their  differences.  Look 
for  crescent  cells  or  "demilunes  of  Heidenhein."  In  which 
glands  are  they  found  ?  What  is  the  difference  between  an 
alveolus  and  an  acinus  ?  Nature  of  the  membrana  propria  about 
the  glands? 

(b)  The  salivary  glands  proper. 

(i)  Examine  a  piece  of  fresh  salivary  gland  under  the  dissecting 
microscope.  Note  color,  lobules  and  alveoli.  Sketch  a  small 
area  of  the  surface.  Now  tease  a  bit  of  the  gland  on  a  slide, 
mount  in  water  and  examine  under  the  compound  microscope. 
Note  the  connective  tissue  frame-work  and  the  arrangement  of 
the  gland  cells.     Sketch  a  single  alveolus. 

(2)  From  a  section  stained  in  hematoxylin  and  congo  red  draw  a 
small  lobule  of  a  parotid  gland  (gl.  parotis)  showing  the  con- 
nective tissue  frame-work,  the  alveoli,  the  intralobular  and  inter- 
lobular ducts  and  including  the  membrana  propria.  The  dis- 
tribution, origin  and  significance  of  the  so-called  basket  cells? 
Judging  from  its  staining  properties,  what  is  the  functional 
nature   of  this  gland?     Under  high   power,   draw  one   or  two 


THE    TEETH.  QI 

alveoli  and  a  duct  in  section.  Why  should  the  two  stain  dif- 
ferently? Include  an  intermediate  (intercallary)  duct  and  note 
the  relative  size  and  position  of   its  cells. 

(3)  Under  high  power,  draw  one  or  two  mucous  alveoli  from  the 
sublingual  gland  (mucous),  or  from  the  submaxillary  gland 
(mixed),  illustrating  the  structure  and  relative  size  of  the  mucous 
cells  and  the  arrangement  and  staining  properties  of  the  demilunes 
of  Heidenhein  (Gianuzzi).  Microchemical  differences  of  the 
latter?     Their  variations  and  significance? 

(4)  From  a  section  of  injected  salivary  gland  make  a  sketch  illus- 
trating the  blood-supply.  What  can  be  said  as  to  its  abundance  ? 
Arrangement  and  abundance  of  capillaries  for  supply  of  alveoli  ? 

(5)  Read  articles  cited  on  the  nerve-supply  of  the  sahvary  glands. 
Type  of  axones?     Distribution  of  telodendria  to  gland  cells? 

5.  The  tonsils. 

(a)  With  mirror  examine  carefully  the  tonsillae  palatina?,  noting  their 
position  and  indications  of  crypts  (recessi)  in  their  surfaces  and 
evidence  of  underlying  lymph-follicles.  What  are  the  dift"erences 
in  gross  appearance  between  the  lingual,  palatine,  and  pharyngeal 
tonsils  ? 

(b)  From  a  section  of  the  palatine  tonsil  draw  a  region  containing  and 
surrounding  a  crypt  or  recess,  paying  attention  to  the  modifications 
of  the  mucous  membrane.  What  is  the  tonsil  as  an  organ  ?  Make 
a  high  power  drawing  showing  the  pecuharity  of  mucous  mem- 
brane of  the  recess  and  the  tissue  underlying  it.  What  can  be 
said  of  the  tela  submucosa?     Invasion  of  leukocytes? 

6.  The  teeth. 

(a)  State  the  number,  names,  and  positions  of  the  teeth.  Differences 
between  deciduous  and  permanent  teeth?  With  a  mirror  observe 
evenness  of  the  corona  dentis  of  the  incisors  and  the  tuberculae 
coronae  dentis  of  the  molars.  What  is  the  neck  of  the  tooth  (collum 
dentis)  ? 

(b)  Under  low  power,  make  a  drawing  of  a  ground  longitudinal  section 
of  one  of  the  incisors,  showdng  the  enamel  (substantia  adamantina) 
with  the  appearances  which  characterize  it,  the  cementum  (sub- 
stantia ossea  dentis),  the  dentin  (substantia  eburnea),  and  the  pulp 
cavity  (cavum  dentis).  Is  there  a  foramen  apicis  dentis ?  How  does 
the  collum  dentis  differ  from  the  other  parts  ? 

(c)  Under  high  power,  make  a  drawing  of  a  segment  of  the  section 
including  the  enamel  (sub.  adamantina),  and  passing  to  the  pulp 
cavity.  What  are  the  dift'erences  between  the  enamel  fibers  and 
the  dentinal  tubules?     What  is  the  nature  of  the  zone  di\iding  the 


92  LABORATORY    GUIDE    FOR    HISTOLOGY. 

two?  What  is  the  behavior  of  the  tubules  upon  approaching  this 
zone?  What  are  the  lines  of  Retzius  and  the  lines  of  Schraeger? 
Significance  of  interglobular  spaces  ? 

(d)  Make  a  careful  drawing  of  a  portion  of  the  cementum  (sub.  ossea) 
where  it  is  thickest.  In  what  does  it  differ  from  the  other  parts 
of  the  tooth  in  texture,  structure  and  origin?  Significance  of 
Tomes'  granular  layer? 

(e)  Development  oj  the  teeth. 

(i)  Read  carefully  the  texts  and  articles  cited  and  fix  in  mind,  in 
their  natural  sequence,  the  various  stages  in  the  development 
of  the  teeth  from  the  earliest  indications  to  the  time  of  emergence. 
Make  a  table  showing  the  average  ages  of  the  infant  at  which 
the  various  teeth  emerge. 

(2)  From  sections  made  transverse  to  the  jaws  of  fetuses  of  different 
ages  (pig),  make  sketches  illustrating  first,  the  origin  of  the 
enamel  germ;  second,  the  formation  of  the  dentinal  papilla  and 
the  dental  lamina  connecting  the  germ  with  the  dental  furrow. 
From  a  vertical  section  through  one  of  the  developing  incisors 
draw  under  low  power  showing,  third,  the  differentiation  of  odon- 
toblasts and  adamantoblasts,  the  formation  of  the  enamel  pulp, 
the  outer  epithelium  of  the  enamel  organ,  and  the  germ  of  the 
permanent  tooth.  Fourth,  from  a  similar  section  through  a 
later  stage,  draw  the  enamel  organ  alone  showing  the  beginning 
formation  of  enamel  and  dentin.  Fifth,  under  high  power 
draw  a  few  adamantoblasts  and  odontoblasts  showing  their 
differences,  relative  positions  and  products. 

What  is  the  origin  and  significance  of  the  membrana  pra^formi- 
tiva?  Relative  shape,  size  and  arrangement  of  adamantoblasts 
and  adontoblasts?  How  is  the  germ  of  the  permanent  tooth 
connected  with  the  enamel  organ  of  the  deciduous  tooth  and 
with  the  oral  epithelium?  Nature  of  the  dental  ledge?  Differ- 
ences between  enamel  pulp  and  tissue  contained  in  dentinal 
papilla  (dental  pulp)  ?     What  occupies  the  dentinal  tubules  ? 

B.  The  Pharynx  and  Esophagus. 

1.  Fresh.  Note  the  extent  and  variations  .of  the  tube  in  position. 
Remove  a  small  piece  of  the  fresh  esophagus  and  tease  it  in  salt 
solution  under  the  dissecting  microscope,  identifying  the  following 
coats:  epithelium,  tela  submucosa,  tunica  muscularis  with  its  stratum 
circulare  and  stratum  longitudinale,  and  the  tunica  adventitia. 

2.  Draw  a  segment  of  a  stained  transverse  section  taken  through  the 
pharynx,  and  then  of  one  taken  through  the  lower  third  of  the 
esophagus.       First    study    the    sections   carefully,   noting    all    dif- 


FUNDUS    GLANDS.  93 

ferences  between  the  two.  What  is  the  nature  of  the  epithelium? 
At  which  level  are  glands  most  abundant?  What  is  the  nature 
of  the  glands  and  how  do  their  secretions  reach  the  surface? 
Where  and  how  does  the  muscularis  (lamina)  mucosae  begin? 
What  differences  are  to  be  noted  in  the  outer  muscle  layers 
(strata)  of  the  two  sections?  Look  for  superficial  esophageal 
glands.  Where  and  how  are  these  situated  ?  Show  their  structure. 
Significance  ? 

C.   The  Stomach  {ventriculus,  gaster). 

•I.  Clip  out  a  small  block  of  the  wall  of  a  fresh  stomach  (dog)  and 
place  it  in  normal  salt  under  a  dissecting  lens. 

(a)  With  a  pipette  wash  off  the  debris  from  the  glandular  surface  and 
observe  the  epithelium  closely.  Make  a  careful  sketch  of  a  small 
area  showing  the  orifices  of  gastric  crypts  ? 

(b)  Now  tease  the  specimen,  identifying  the  following  tunics:  epithe- 
lium, lamina  propria  mucosae,  muscularis  mucosas,  tela  sub- 
mucosa,  tunica  muscularis  consisting  of  stratum  circulare  and 
stratum  longitudinale,  and  finally,  tunica  serosa.  Are  fibrs 
obliquae  10  be  noted?  In  what  region  of  the  stomach  are  they 
present  ? 

2.  From  a  section  (stained)  passing  vertically  through    the  junction  of 

the  esophagus  and  stomach  (cardia),  make  a  drawing  under  low 
power  showing  the  transition  of  the  epithelium  of  the  one  into  that 
of  the  other  and  the  change  in  the  character  of  the  glands. 

3.  Cardiac   Glands. — Make    a   small  drawing  showing  in   detail  the 

structure  of  these  glands.  Parietal  cells?  Goblet  cells?  Signifi- 
cance of    the    glands?     Extent  of  area  occupied? 

4.  Fundus  Glands. — From    a   section    taken    vertically    through  the 

wall  of  the  fundus  ventriculi,  make  a  drawing  one  or  two  gastric 
crypts  in  width  and  involving  all  the  tunics,  including  the  tunica 
serosa.  How  many  glands  open  into  a  single  crypt  ?  What  is  the 
relative  abundance,  position  and  staining  qualities  of  the  parietal 
or  oxyntic  (delomorphous)  cells  as  compared  with  the  chief  or 
peptic  cells?  What  is  the  extent  of  the  mucosa  (lamina  propria) 
and  the  relative  thickness  of  the  tela  submucosa?  What  con- 
stitutes the  mucous  membrane?  Under  high  power  draw  a  small 
part  of  one  of  the  longitudinally  cut  glands,  showing  in  detail  the 
relation  and  structure  of  the  parietal  and  chief  cells,  and  their  re- 
lation to  the  basement  membrane.  In  what  part  of  the  cells  are 
the  nuclei  situated?  Are  granule  cells  of  Paneth  present?  To 
what  tunic  belongs  the  tissue  just  under  the  basement  membrane? 


94  LABORATORY    GUIDE    FOR    HISTOLOGY. 

5.  Draw  a  small  segment  of  a  fundus  gland  prepared  by  the  Golgi 

method,  showing  the  lumen  of  the  gland  and  the  secretory  duct 
and  secretory  capillaries  of  two  or  three  parietal  cells.  Do  all  the 
cells  have  a  duct?  What  is  indicated  by  the  occurrence  of  a  duct 
and  capillaries?  Are  the  adelomorphous  cells  affected  by  the 
silver?     Why? 

6.  Pyloric  Glands. — ^From   a   section  taken   transversely  through  the 

wall  of  the  pars  pylorica,  make  a  drawing  including  the  mucous 
membrane  only,  and  showing  the  form  and  nature  of  the  glands 
(glandulse  pyloricae).  Closely  observe  and  enumerate  all  the 
features  in  which  this  region  differs  from  that  of  the  fundus. 
Evidences  that  one  of  the  chief  functions  of  the  pyloric  glands  is 
mucous  secretion  ? 

D.  The  Intestine. 

1.  Duodenum. — Under  low  power  sketch  a  section  passing  longitudinally 

through  the  pylorus  and  involving  a  portion  of  the  pars  pylorica  ven- 
triculi  on  the  one  side,  and  the  duodenum  on  the  other.  Give 
special  attention  to  the  zone  of  transition  of  the  mucous  membrane, 
the  abundance  and  position  of  Brunner's  glands  (glandulse  duode- 
nales)  and  the  M.  sphincter  pylori.  What  constitute  the  differ- 
ences in  the  epithelium?  What  is  the  functional  nature  of  Brun- 
ner's glands?  What  muscle  stratum  enters  chiefly  into  the  forma- 
tion of  the  sphincter  pylori  ?  Occurrence  and  origin  of  muscularis 
mucosas  ? 

2.  Small  intestine  (intestimim  tenite). 

(a)  From  a  transverse  section  either  of  jejunum  or  illeum,  make  a 
drawing  showing  one  or  two  villi  and  the  adjacent  crypts  of  Lieber- 
kuehn,  and  including  all  the  tunics.  What  is  the  relation  of  the 
stratum  proprium  (lamina  propria)  to  the  villus?  Muscularis 
mucosae?  What  of  the  staining  qualities,  position,  shape  and 
distribution  of  the  goblet  cells?  Does  the  section  involve  a  Pyer's 
patch?  What  are  these  and  where  situated?  Granule  cells  of 
Paneth  ? 

(b)  Under  high  power  draw  a  few  of  the  epithelial  cells  of  a  villus 
including  a  goblet  cell  and  a  portion  of  the  villus  axis.  Granule 
cells  of  Paneth,  their  position  and  significance  ?  Is  there  a  striated 
cuticular  zone?  Basement  membrane?  What  is  the  structure 
of  the  goblet  cell  and  how  does  it  differ  from  the  chief  cell  ?  What 
are  the  differences  between  the  mucous  membrane  of  the  jejunum 
and  illeum? 


NERVE-SUPPLY    OF    DIGESTIVE    CAXAL.  95 

3.  Large  intestine  {intestinum  crassum). 

(a)  Make  a  drawing  from  a  transverse  section  of  the  large  intestine 
including  only  the  mucous  membrane  and  showing  one  or  two  of 
the  glands  of  Lieberkuehn.  Let  this  or  a  separate  drawing  show  a 
solitary  lymph  follicle.  Make  a  detailed  comparison  between  the 
arrangement  of  the  epithelium  here  and  that  of  the  small  in- 
testine. How  do  the  goblet  cells  differ?  What  is  the  arrangement 
of  the  epithelium  lying  over  the  "solitary  lymph-gland?"  How 
does  the  tunica  muscularis  differ  from  that  of  the  small  intestine 
and  how  are  the  taenia  and  haustra  coli  produced  ? 

4.  Appendix  {processus  vermijormis). 

(a)  Draw  showing  a  portion  of  a  transverse  section  from  a  normal 
specimen.  Note  and  show  the  nature  and  condition  of  the 
epithelium,  the  relative  abundance  of  the  lymphatic  follicles  and 
the  modifications  of  the  tunica  muscularis  as  compared  with  the 
small  intestine.  Muscularis  mucosae  ?  Size  of  the  lumen  ?  Sig- 
nificance of  the  structure  of  the  appendix  ?     Its  origin  ? 

E.  Rectum  and  Anus. 

I.  Sketch  a  longitudinal  section  showing  the  transition  of  the  epithelium 
of  the  rectum  into  that  of  the  anus.  Type  and  arrangement  of 
the  glands?  Li  what  does  the  rectum  differ  from  the  large 
intestine?  Modifications  of  the  musculature  of  the  anus  from 
that  of  the  rectum?  Striated  muscle?  Nature  of  anal  glands 
proper? 

F.  Blood-supply  of  the  Digestive  Canal. 

I.  From  a  section  of  an  injected  stomach  or  intestine,  sketch  a  small 
area  showing  the  blood-supply  as  distributed  to  the  various 
tunics.  Note  that  the  vessels,  entering  by  way  of  the  mesenteric 
attachment,  form  (a)  the  intermuscular  plexus  and  (b)  the  plexus 
of  Heller.  The  latter  supplies  the  mucous  membrane.  What  can 
be  said  of  the  relative  blood-supply  of  the  dift'erent  tunics? 
What  is  the  general  arrangement  of  the  lymph-vessels  of  the 
digestive  tract? 

G.  Nerve-supply  of  the  Digestive  Canal. 

1.  Examine  all  sections  of  the  canal  supplied,   (a)  between  the  strata 

of  the  tunica  muscularis  for  nerve-cells  belonging  to  Auerbach's 
plexus  (plexus  myentericus)  and  (b)  in  the  tela  submucosa  for 
cells  belonging  to  ^Meissner's  plexus  (plexus  submucosa).  Sketch  a 
group  of  cells  showing  its  surroundings. 

2.  Tease  apart  the  above  tunics  of  a  piece  of  a  stomach  or  intestine, 

which  has  been  stained  with  gold  chlorid;  mount  bits  of  both  the 


96  LABORATORY    GUIDE    FOR    HISTOLOGY. 

submucosa  and  tunica  muscularis  in  glycerin  and  examine  for  the 
above  named  plexuses.  Sketch  showing  ganglia  and  the  arrange- 
ment of  the  nerve  fasciculi  forming  the  pJexuses.  What  is  the 
shape  of  the  ganglion  cells?  Signiiicance  of  the  plexuses?  Nature 
and  origin  of  cerebrospinal  axones  supplying  the  digestive  canal? 

H.  The  Liver  {he par). 

1.  The  fresh  specimen. 

(a)  With  the  organ  in  position  in  the  body,  note  its  lobes,  right  and 
left;  its  relations  to  the  diaphragm,  duodenum,  stomach,  kidneys 
and  colon.  What  is  the  color  of  the  organ?  How  is  the  vena 
cava  inferior  attached  to  the  organ?  Note  the  entrance  of  vena 
portse.     From  what  visceral  veins  is  it  derived  ? 

(b)  Remove  the  liver  from  the  subject  and  identify  the  following 
structures:  lobus  dexter,  lobus  sinister,  and  lobus  caudatus;  vena 
portae  with  right  and  left  divisions;  vena  cava  inferior  with  venae 
hepaticae  dextra  and  sinistra;  arteria  hepatica  with  right  and  left 
divisions;  ductus  hepaticus,  ductus  cysticus,  ductus  choledochus 
(common  bile  duct),  and  vesica  fellea  (gall  cyst).  Trace  the 
ductus  choledochus.  Into  what  does  it  open?  Open  the  gall 
cyst,  and  with  lens  note  plicae  tunicae  mucosae.  Split  the  cystic 
duct  and  observe  the  valvula  spiralis.  What  is  the  nature  of  its 
formation?  Note  lig.  teres,  and  on  anterior  surface,  lig.  falci- 
forme  hepatis  and  lig.  coronarium  hepatis. 

(c)  With  dissecting  lens,  examine  the  surface  of  the  fresh  liver,  noting 
its  general  appearance  and  the  indication  of  lobules.  Remove  a 
wedge  of  the  organ  and  tease  in  salt  solution.  What  is  the  approx- 
imate size  of  the  granules  and  what  are  they?  What  can  be  said 
of  the  abundance  of  the  frame-work  ? 

2.  Sections. 

(a)  Injected  (dog  or  cat).  Under  low  power  draw  a  single  lobule 
or  hepatic  unit  in  transverse  section,  showing  its  shape  and  relation 
'to  adjacent  lobules,  the  venae  interlobulares  and  the  anastomosing 
system  of  intralobular  capillaries  converging  into  the  intralobular 
vein  or  vena  centralis.  Note  anastomoses  of  capillaries  in  the 
third  dimension.  Draw  in  some  of  the  liver  cells.  Look  for 
a  lobule  cut  longitudinally  and  thus  showing  the  vena  sublobularis. 
What  is  the  relation  of  the  latter  to  the  vena  centralis  and  to  the 
hepatic  vein  ?  What  is  the  course  of  the  blood  borne  by  the  hepatic 
artery?  Note  the  interlobular  capsulae  fibrosae,  or  capsules  of 
Glisson,  and  their  surroundings  and  identify  the  three  larger  vessels 
contained.     What  are  "portal  canals?" 


THE    GALL-BLADDER.  97 

(b)  Stained  sections  (human  and  pig).  Under  high  power  draw  (i) 
a  quadrant  of  a  lobule  including  the  vena  centralis  and  the  portion 
of  the  interlobular  frame-work  and  vessels  involved.  AVhat  is  the 
arrangement  and  thickness  of  the  columns  of  liver  cells  (hepatic 
cords)  and  what  is  their  relation  to  the  capillaries?  The  relation 
of  the  individual  cell  to  the  capillary  wall?  Note  occasional 
"Stellate  cells  of  Kupffer"  and  look  for  evidences  that  they  serve 
as  a  partial  endothehal  Hning  of  the  capillaries  and  that  they  con- 
sist of  a  syncytium  of  epithehal  cells.  (2)  With  oil  immersion, 
draw  two  or  three  cells  showing  their  internal  structure  in  detail. 
Do  they  possess  cell  membranes?  Relation  to  bile  capillaries? 
Look  for  secretory  channels  (bile  canaliculi).  Nature  of  the 
granules?  Evidence  of  fat  globules?  Pigment?  In  what  func- 
tional stage  are  the  cells  ?  What  can  be  said  of  cell  division  in  the 
liver?  (3)  Draw  a  capsule  of  Glisson.  What  structural  differ- 
ences distinguish  the  three  types  of  larger  vessels  it  contains? 
How  do  the  larger  bile  ducts  differ  from  the  smaller?  In  what 
does  the  human  liver  differ  from  that  of  the  hog  ? 

(c)  Golgi  preparation.  Draw  a  quadrant  of  a  lobule  (hepatic  unit) 
showing  the  intralobular  net-work  of  bile  capillaries  as  differ- 
entiated by  silver,  choosing  an  area  which  shows  the  capillaries  con- 
tinuous into  an  interlobular  bile  duct.  Look  for  bile  canaliculi. 
Explain  their  occurrence. 

(d)  Frame-work  of  the  liver.  Either  digested  preparation  or  one 
specially  stained  for  the  frame-work.  Draw  illustrating  the  abun- 
dance, quality,  and  arrangement  of  the  connective-tissue  frame-work 
of  a  lobule  and  the  adjacent  interlobular  tissue.  What  variety 
of  fibrous  connective  tissue  predominates?  What  is  the  relation 
of  the  fibers  to  the  liver  cells  and  to  the  course  and  structure  of  the 
intralobular  blood  capillaries.  Since  no  typical  connective-tissue 
"cells"  are  to  be  observed  within  the  lobules  in  any  of  the  prep- 
arations, whence  arises  the  intralobular  frame-work  ? 
Distinguish  between  the  hepatic  unit  (blood-vascular  unit)  and  the 
portal  unit  (secretory  unit)  and,  on  the  basis  of  development  and 
function,  show  which  of  these  units  can  with  more  reason  be  con- 
sidered the  unit  of  structure  of  the  liver. 

3.  The  gall-bladder  {vesica  jellea). 

(a)  Macroscopic.  From  a  fresh  specimen  (ox  or  hog)  or  from  a  gall- 
bladder which  has  been  fixed  and  dried  distended  (human),  identify 
the  ductus  choledochus,  ductus  hepaticus,  ductus  cysticus,  and  the 
shape  and  relative  position  of  the  vesica  fellea.  What  is  the  direc- 
tion of  the  connection  with  the  duodenum?  Beginning  with  the 
collum  vesica?,  note  indications  of  the  spiral  (Heisterian)  valve. 


98  LABORATORY    GUIDE    FOR    HISTOLOGY. 

Open  the  fresh  gall-bladder  and  note  the  numerous,  irregular 
polygonal  depressions  produced  by  the  continuous  system  of  per- 
manent corrugations  or  folds  of  the  mucosa, 
(b)  Under -high  power  draw  a  portion  of  a  stained  vertical  section  of  the 
wall  of  the  gall-bladder,  showing  all  of  the  tunics.  Evidence  that 
the  corrugations  are  permanent  ?  Type  of  the  epithelium  ?  Goblet 
cells?  Indications  of  fat  globules?  Lymphatic  nodes  and  indi- 
cations of  lymphatic  vessels?  Into  how  many  and  what  strata 
may  the  muscle  of  the  fibro-muscular  tunic  be  arranged?  What  is 
the  extent  and  origin  of  the  tunica  serosa?  Variations  in  the 
wall  in  different  regions?     Mucous  glands? 

I.  Pancreas. 

1.  Macroscopic. 

(a)  Observe  the  organ  in  position  (dog  or  cat).  What  is  its  relation 
to  the  stomach  and  duodenum?  Color?  Identify  caput,  cauda  and 
ductus  pancreaticus.  What  part  of  the  duodenum  does  the  duct 
enter?  Note  that  the  gland  is  divided  into  lobes  held  together  by 
ingrowths  of  its  capsule  (membrana  propria).  Make  a  sketch 
illustrating  the  surface  appearance  of  a  lobe. 

(b)  Tease  a  bit  in  salt  solution,  mount  and  examine  under  high  power. 
What  is  the  shape  and  arrangement  of  the  gland  cells?  Note 
that  the  shape  of  the  alveolus  suggests  the  name  "acinus." 

2.  Stained  sections. 

(a)  Under  high  power  draw  a  transverse  section  of  a  duct  and  one  or 
two  alveoli  showing  "centro-acinar"  cells  and  an  intermediate 
(intercallary)  duct.  How  do  the  ducts  differ  from  the  alveoli? 
Do  the  cells  of  the  alveoli  have  an  inner  granular  zone  ?  Explain 
it?  Position  of  the  nuclei?  Note  that  the  larger  ducts  are  lined 
either  by  pseudo-stratified  or  stratified  columnar  epithelium.  Is 
there  any  muscle  in  their  walls? 

(b)  Sketch  one  of  the  intralobular  cell  masses  or  ^^  islands  of  Langer- 
hans,"  including  the  tissue  immediately  surrounding  it.  Describe 
it.  What  varieties  of  cells  compose  it?  What  is  its  origin  and 
significance  and  what  is  its  shape  as  shown  by  reconstruction  ? 
In  what  part  of  the  pancreas  are  these  cell  masses  most  abundant  ? 
What  gland  previously  studied  does  the  pancreas  most  resemble  in 
structure  and  function  ?     State  five  particulars  in  which  the  two  differ. 

(c)  Frame-work.  From  a  thick  section  of  digested  pancreas  stained 
with  fuchsin  or  analin  blue,  draw  under  low  power  an  area  involving 
an  island  of  Langerhans.  What  is  the  relation  of  the  connective 
tissue  fibres  to  the  alveolar  cells  and  to  the  ducts?  What  is  the 
significance  of  the  especially  abundant  frame-work  of  the  islands  ? 


LITERATURE.  99 

LITERATURE  ON  THE  DIGESTIVE  APPARATUS. 
Mouth  Cavity. 

ADLOFF,   P.     Zur  Entwicklungsgeschichte  des  Zahnsystems  von   Sus   scrofa   domestica. 

Anat.  Anz.,  Bd.  19,  p.  481,  1901. 
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Bd.  14,  p.  343,  1898. 

Esophagus. 

De  WITT,  L.  M.     Arrangement  and  Terminations  of  Nerves  in  the  Esophagus  of  Mammalia. 

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Pharynx  und  Oesophagus.     Arch.  f.  Wiss.  u.  Prakt.  Tierheilk.,  Bd.  31,  H.  4-5,  p. 

466,  1905. 
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\'ol.  5,  No.  4,  1901. 
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H.  3,  p.  562,  1905. 


lOO  LABORATORY    GUIDE    FOR   HISTOLOGY. 

Stomach. 

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1902. 
DEKHUYZEN,  M.  C,  and  VERMACH,  P.     Ueber  das  Epithel  der  Oberflache  des  Magens. 

Verhandl.  d.  Anat.  GeselL,  Bd.  17,  p.  145,  1903. 
DE  WITT,  L.  M.     Morphology  of  the  Pyloric  Glands  as  Shown  by  Reconstruction.     Am. 

Jour.  Anat.,  Vol.  i,  p.  514,  1902. 
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Arterien  derselben.     Arch.  f.  Mik.  Anat.,  Bd.  63,  H.  3,  1904. 
HAANE,  G.     Ueber  die   Cardiadriisen  und   die   Cardiadriisenzone  des  Magens  der  Haus- 

saugetiere.     Arch.  f.  Anat.  u.  Physol.,  Anat.  Abt.,  Jg.  1905,  H.  i,  p.  i. 
VON  DER  LEYEN,  E.     Ueber  die  Schleimzone  des  Menschlichen  Magen  und  Darmepithels 

vor  und  nach  der  Geburt.     Virchow's  Arch.  f.  Pathol.  Anat.,  Bd.  180  (Folge  17,  Bd. 

18),  H.  I,  p.  99,  1905. 
LIEBERT,  A.     Ueber   die    Fundusdrlisen  des  Magens  beim  Rhesus  Affen.     Anat.  Hefte, 

Abt.  I,  H.  73  (Bd.  23,  H.  3),  p.  495,  1904. 
MALL,  F.  P.     The  Vessels  and  Walls  of  the  Dog's  Stomach.     Johns  Hopkins  Hosp.  Rep., 

Vol.  I,  p.  I,  1896. 
MAY,  W.  P.     The  Innervation  of  Sphincters  and  Musculature  of  the  Stomach.     Jour,  of 

Physiol.,  Vol.  31,  No.  3-4,  p.  260,  1904. 
NOLL,  A.,  and  SOKOLOFF,  A.     Zur  Histologie  der  ruhenden  und  tatigen  Fundusdriisen 

des  Magens.     Arch.  f.  Anat.  u.  Physiol.,  Physiol.  Abt.,  Jg.  1905,  H.  1-2,  p.  94. 
PIRONE,  R.     Recherches  sur  la  fonction  secretione  des  cellules  glandulaires  gastriques. 

Zeit.  f.  allg.  Physiol.,  Bd.  4,  H.  i,  p.  62,  1904. 
SCHRIDDE,  H.     Ueber   Magenschleimhaut-Inseln  vbm   Bau   der  Cardialdriisenzone  und 

Fundusdriisenregion    und    den    unteren    oesophagealen    Cardialdriisen   gleichende 

Drtisen  im  obersten   Oesophagusabschnitt.     Virchow's  Arch.  f.  pathol.  Anat.  Bd. 

175  (Folge  17,  Bd.  5),  H.  i,  p.  i,  1904. 
STRECKER,  F.,  and  CASSE,  C.     Der  menschliche  Magen.     Archiv.  fiir  Anat.  u.  Physiol., 

Anat.  Abt.,  Jg.  1905,  H.  i,  p.  2^. 
WERNSTEDT,    W.     Grundform    und    Kontraktionsformen    des    menschlichen    Magens. 

Einige  Gesichtspunkte  fiir  das  Studium  der  form  des  Magens  und  der  Benennung 

seiner  Telle.     Arch.  f.  Anat.  u.  Phys.,  Anat.  Abt.,  H.  3-4,  p.  120,  1907. 

Intestine. 

ANCEL,  P.  Sur  les  mesocolons  ascendant  et  descendant  et  leur  mode  de  formation  chez 
I'homme.     Compt.  rend.  Assoc.  Anat.,  9  Reun,  Lille,  p.  i,  1907. 

ARCANGELI,  A.  Ricerche  suU'assorbimento  intestinale.  Atti.  Congr.  Natural.  Ital., 
Milano,  1906,  Ersch.  p.  576,  1907. 

ARNOLD,  J.  Weitere  Beispiele  granularer  Fettsynthese  (Zungen  und  Darmschleimenhaut). 
Anat.  Anz.,  Bd.  24,  p.  389,  1904. 

BENSLEY,  R.  R.  On  the  Histology  of  the  Glands  of  Brunner.  Am.  Jour.  Anat.,  Vol.  2, 
1902. 

BENSLEY,  R.  R.  The  Structure  of  the  Glands  of  Brunner.  Univ.  Chicago  Decennial 
Publications,  Vol.  10,  1903. 

BOGOMOLETZ,  A.  A.  Beitrag  zur  Morphologic  und  Mikrophysiologie  der  Brunnerschen 
Driisen.     Arch,  fiir  Mik.  Anat.,  Bd.  61,  p.  656,  1903. 

BRAUN,  W.  O.  Untersuchungen  uber  das  Tegument  der  Analoffnung.  •  Inaugural  Dis- 
sertation, R.  Leupold,  Konigsberg,  1901. 

BRUEHL,  L.  J.  Beitrage  zur  Lehre  von  den  Becherzellen.  Inaugural  Dissertation.  Ed- 
mund Stein,  Potsdam,  1898. 

COOKE,  A.  B.  A  Study  of  the  Rectal  Valve,  Experimental  and  Chnical.  Phil.  Med.  Jour., 
Vol.  5,  p.  964,  1900. 

DUBOIS,  C.  C.  Granule  Cells  in  the  Mucosa  of  the  Pig's  Intestine.  Anat.  Anz.,  Bd.  25, 
p.  6,  1904. 

KLEIN,  S.  On  the  Nature  of  the  Granule  Cells  of  Paneth  in  the  Intestinal  Glands  of  Mam- 
mals.    Am.  Jour,  of  Anat.,  Vol.  5,  No.  3,  p.  315,  1906. 

LOEVENHART,  A.  S.  On  the  Relation  of  Lipase  to  Fat  Metabolism — Lipogenesis.  Am. 
Jour.  Phy.siol.,  Vol.  6,  p.  331,  1902. 

MERIEL,  E.  L'appendice  senile  etude  anatomique  et  clinique.  Rev.  de  Gynecol,  et  de 
Chir.  Abdominale,  T.  11,  No.  2,  p.  329,  1907. 

PFLUEGER,  E.  Ueber  Kalkseifen  als  IBeweise  gegen  die  in  wasseriger  Losung  sich  voil- 
ziehende  Resorption  der  Fett.     Pfliiger's  Archiv.,  Bd.  89,  p.,  211,  1902. 

REUTER,  K.     Ein  Beitrag  zur  Frage  der  Darmresorption.     Anat.  Hefte,  Bd.  21,  p.  121,  1903. 


LITERATURE.  lOI 

Liver. 

ARNOLD,  J.     Zur  Kenntnisse  der  Granula  der  Leberzellen.     x\nat.  Anz.,  Bd.  20,  p.  226, 

1901. 
BALCH,  A.  W.,  and  PFAFF,  F.     An  Experimental  Investigation  of  Some  of  the  Conditions 

Influencing  the  Secretion  and  Composition  of  Human  Bile.     Jour,  of  Exper.  Med., 

VoL  2,  No.  I,  1897. 
BRISSAUD   et   BAUER.     A.  propos  de  I'independance   des  lobes  du  foie.     Compt.  rend. 

Soc.  Biol.,  T.  62,  No.  23,  p.  1202,  1907. 
HASSE,   C.     Die   Mundungen   der  Lebervenen  vor  und  nach  der  Geburt.     Ein  weiterer 

Beitrag  zur  Lehre  von  dem  Einfluss  der  Atmung  auf  die   Organe  des  K5rpers. 

Arch.  f.  Anat.  und  Physiol.,  Anat.  Abt.,  p.  209,  1907. 
HENDRICKSON,  W.  F.     The  Development  of  the  Bile  Capillaries  as  Revealed  by  Golgi's 

Method.     Johns  Hopkins  Hosp.  Bull.,  Vol.  9,  p.  220,  1S98. 
HENDRICKSON,  W.  F.     A  Study  of  the  Musculature  of  the  Entire  Extrahepatic  Bilar}' 

System,  Including  that  of  the  Duodenal  Portion  of  the  Common  Bile  Duct  and  of 

the  Sphincter.     Johns-Hopkins  Hosp.  Bull.,  Vol.  9,  p.  221,  1898. 
HOLMGREN,  E.     Ueber  die  "  Saf tkanalchen "  der  Leberzellen  und  der  Epithelsellen  der 

Nebenniere.     Anat.  Anz.,  Bd.  22,  p.  260,  1902. 
ILLING,  G.     Vergleichend-histologische  Untersuchungen  uber  die  Leber  der  Haussiiuge- 

tiere.     Anat.  Anz.,  Bd.  26,  No.  7-8,  p.  177,  1905. 
KOROLKOW,  P.     Ueber  Nervendigungen  in  der  Leber.     Anat.  Anz.,  Bd.  88,  p.  751,  1893. 
KUPFFER.     Ueber  die  sogenannten  Sternzellen  der^Saugetierleber.     Arch.  f.  Mik.  Anat., 

Bd.  54,  p.  254,  1899. 
MALL,  F.  P.     On  the  Origin  of  the  Lymphatics  in  the  Liver.     Johns  Hopkins  Hosp.  Bull., 

Vol.  12,  p.  146,  1901. 
MALL,  F.  P.     A  Study  of  the  Structural  Unit  of  the  Liver.     Am.  Jour,  of  Anat.,  Vol.  5, 

No.  6,  p.  227,  1906. 
SCHAEFER,  E.  A.     On  the  Existence,  Within  the  Liver  Cells,  of  Canaliculi  Which  are  in 

Direct  Communication  with  the  Blood  Capillaries.     Jour.  Physiol.,  Vol.  27,  1902. 
SUDLER,  M.  T.     The  Architecture  of  the  Gall-bladder.     Johns  Hopkins  Hosp.  Bull.,  Vol. 

12,  p.  126,  1901. 
WACE,  C.  E.     De  certains  changements  qui  peuvent  etre  observes  dans  les  cellules  du  foie 

pendant  la  digestion  et  de  leurs  relations  avec  la  secretion   hepatique.     Cornpt. 

rend.  Assoc.  Anat.,  9  Reun,  Lille,  p,  147,  1907. 

Pancreas. 

BARTELS,   P.     Ueber    die    Lymphgefasse  des  Pankreas.     2.   Das  feinere  Verhalten  der 

lymphatischen    Verbin'dungen     zwischen     Pankreas     und     Duodenum.     Arch.    f. 

Anat.  u.  Physiol.,  Anat.  Abt.,  Jg.  1906;  H.  4-5,  p.  250. 
DALE,  H.  H.     The'  Islets  of  Langerhans  of  the  Pancreas.     Proc.  of  the  R.  Soc,  \'ol.  73, 

No.  489,  p.  84,  1904. 
DEWITT,  L.  M.     Morphology  and  Physiology  of  Areas  of  Langerhans  in  some  \'ertebrates. 

Jour,  of  Exper.  Med.,  Vol.  8,  No.  2,  p.  193,  1906. 
DIENLAFE   et  MATHIEU.     Sur  la  topographie  du  pancreas.     Compt.  rend,  de  I'Assoc 

des  Anat.,  8  Reun.,  Bordeaux,  p.  59,  1906. 
HEIBERG,  K.  A.     Ein  Verfahren  zur  Untersuchung  der  Bedeutung  der  Langerhansschen 

Inseln  im  Pankreas.     Hoppe-Seylers  Zeit.  f.  physiol.  Chemie,  Bd.  49,  H.  2-3,  p. 

293,  1906. 
HELLY,  K.     Zur  Frage  der  primaren  Lagebeziehungen  beider  Pankreasanlagen  des  Men 

schen.     Arch.  f.  Mik.  Anat.,  Bd.  63,  PL  3,  1904. 
JACKSON,   C.  M.     On  the  Topography  of    the    Pancreas  in  the  Human  Fetus.     Anat. 

Anz.,  Bd.  28,  Nos.  20-21,  p.  488,  1905. 
KUSTER,  H.     Zur  Entwicklungsgeschichte  der  Langerhans'schen  Inseln  im  Pankreas  beim 

mensclilichen  Embryo.     Arch.  f.  Mik.  Anat.,  Bd.  64,  H.  i,  1904. 
LAGUESSE,  E.     Lobule  et  tissu  conjonctif  dans  le  pancreas  de  I'homme.     Compt.  rend. 

Soc.  Biol.,  T.  58,  No.  12,  p.  539,  1905. 
LANE,  M.  A.     The  Cytological  Characters  of  the  Areas  of  Langerhans.     Am.  Jour.  Anat., 

Vol.  7,  No.  3,  p.  409,  1907. 
OGATA,  M.     Die  Veranderungen  der  Pankreas  bei  der  Sekretion.     Arch.  f.  Physiol.,  p. 

405,  1883. 
OPIE.     On  the  Relation  of  Chronic  Interstitial  Pancreatitis  to  the  Islands  of  Langerhans 

and  to  Diabetes  Mellitus.     Jour.  E.xp.  Med.,  Vol.  5,  No.  4,  1901.     See  also  ibid.. 

Vol.  5,  No.  5. 
PEARCE,  R.  M.     The  Development  of  the  Islands  of  Langerhans  in  the  Human  Embryo. 

Am.  Jour,  of  Anat.,  Vol.  2,  No.  4,  1903. 


I02  LABORATORY    GUIDE    FOR    HISTOLOGY. 

RENNIE,  J.     The  Epithelial  Islets  of  the  Pancreas  in  Teleostei.     Quart.  Jour,  of  Microsc 

Sc,  N.  Ser.,  No.  191,  p.  379,  1904-  ^       ^  .  a      .    w  1       tvt 

REVELL,  D.  G.     The  Pancreatic  Ducts  in  the  Dog.     Am.  Jour,  of  Anat.,  Vol.  i,  JNo.  4, 1902. 
SERENl/s.     Ricerche  sul  "Nebenkern"  delle  cellule  pancreatiche.     Boll.  Soc.  Lancisiana 

Ospidale,  Roma,  Anno  20,  Ease.  2,  1905.  ,  ,  .     ^  ■,  ^^ 

THY^NG,  F.  W.     Models  of  the  Pancreas  in  Embryos  of  the  Pig,  Rabbit,  Cat,  and  Man. 

Am.  Journ.  Anat.,  Vol.  7,  No.  4,  1908.  .     i,    jr 

VOELKER,  O.     Ueber  die  Verlagerung  des  dorsalen  Pankreas  beim  Menschen.     Arch.  t. 

Mik.  Anat.,  Bd.  62,  1903. 


III.  THE  RESPIRATORY  APPARATUS. 
(ninth  paper.) 

A.  Appearance  in  Fresh. 

1.  Saw  transversely  through  the  nares  (dog).  Note  the  paired  cavity  lined 
with  a  thick  mucous  membrane  and  the  means  by  which  the  area  of 
this  membrane  is  increased.  Are  glands  observable  ?  With  what  cavities 
is  the  cavum  nasi  continuous? 

2.  Examine  the  larynx,  trachea  and  lungs  in  position  in  the  body  (dog 
or  human),  identifying  the  single  and  paired  cartilages  of  the  larynx 
and  their  relation  to  the  hyoid  bone,  and  note  the  glandula  thyreoidea 
and  thymus  and  the  laryngeal  muscles;  the  trachea,  its  relation  to  the 
esophagus,  and  the  number  and  shape  of  its  semilunar  cartilages. 
Where  are  the  free  ends  of  the  tracheal  cartilages?  Where  are  the 
glandulas  tracheae?  Note  the  right  .and  left  bronchus  to  right  and  left 
lung.  Right  and  left  pulmonary  arteries  and  veins.  Whence  are 
the  bronchial  arteries  derived? 

3.  Identify  the  lobes  of  the  lung.  With  dissecting  lens  observe  lobules 
and  visceral  pleura.     What  is  the  nature  of  the  latter  ? 

B.  Prepared  Specimens. 

1.  Cavum  nasi. 

(a)  From  a  longitudinal  section  through  the  vestibular  region  make  a 
drawing  showing  the  transition  of  the  vestibular  epithelium  into 
that  of  the  regio  respiratoria.  Note  the  change  in  the  type  of  the 
glands.     Occurrence  and  function  of  hairs? 

(b)  From  a  stained  section  of  the  epithelium  taken  from  the  posterior 
portion  of  the  nasal  cavities,  make  a  drawing  illustrating  the 
character  of  the  epithelium  and  showing  the  structures  present  in 
in  the  mucosa.  What  can  be  said  of  the  nature  and  abundance 
of  the  glands?  Goblet  cells  in  epithelium?  Blood-supply? 
How  does  the  epithelium  here  differ  from  that  in  the  nasus  externus? 
In  what  details  does  it  differ  from  that  of  the  olfactory  region  ? 

2.  Larynx. — Longitudinal    section    passing   transversely    through    the 

vocal  cords  (ligamenta  vocalia).  Draw  under  low  power  showing 
position  and  shape  of  false  and  true  vocal  cords,  their  structure 
and  the  ventricle  of  the  larynx  between  them.  What  is  the 
nature  of  the  epithelium  upon  the  vocal  cords?  What  other 
structures  of  the  larynx  are  similarly  covered?  Where  are  the 
glands  most  abundant?  Lymphoid  tissue?  Which  cartikages  are 
represented  in  the  section  ? 

10^ 


I04  LABORATORY    GUIDE    FOR   HISTOLOGY. 

3.  Trachea  and  Bronchi. — Draw  a  segment  of  a  transverse  section  of 

the  trachea  inchiding  the  ends  of  a  semilunar  cartilage  and  show- 
ing the  annular  ligament  connecting  them  and  the  band  of  trans- 
versely arranged  smooth  muscle.  Note  especially  the  character  of 
the  epithelium,  the  basement  membrane  (membrana  propria),  the 
layer  of  compact  and  circularly  disposed  elastic  tissue  and  the 
looser  fibrous  tissue  next  the  perichondrium  which  contains  the 
glandulte  tracheae.  Goblet  cells?  Where  is  lymphoid  tissue  most 
abundant?  Where  are  the  larger  mucous  glands?  Compare  a 
transverse  section  of  a  bronchus  with  that  of  the  trachea  and 
enumerate  the'  differences  to  be  noted. 

4.  The  lung  {pidmo): 

(a)  From  a  stained  section  of  the  lung  draw  a  transverse  section  of  a 
small  bronchial  ramus,  of  a  bronchiole,  and  of  a  respiratory  bronchiole. 
Give  special  attention  to  the  variations  in  the  epithelium  as  com- 
pared with  that  of  the  trachea  and  bronchus,  and  the  variations 
in  the  occurrence  of  glaiids,  cartilage  and  muscular  tissue.  What 
can  be  said  of  the  disposition  and  relative  abundance  of  the  latter? 
What  characterizes  "respiratory  epithelium?"  Note  the  abundant 
supply  of  arteries,  veins  and  capillaries. 

(b)  From  a  thick  section  of  a  lung  (rat  or  cat)  into  which,  through  the 
trachea,  i  per  cent,  silver  nitrate  has  been  injected,  make  a  drawing 
of  a  pulmonary  alveolus  continuous  into  an  alveolar-  duct  and 
respiratory  bronchiole,  showing  the  nature,  shape  and  variations 
of  the  epithelial  cells  lining  them.  What  is  the  relative  size,  number 
and  position  of  the  nucleated  and  "non-nucleated"  cells?  Look 
for  interalveolar  passages  between  adjacent  alveoli. 

(c)  From  a  Wood's  metal  corrosion  preparation,  break  out  a  twig 
including  a  bronchiolus,  respiratory  bronchiole,  alveolar  ducts, 
infundibula  and  pulmonary  alveoli.  Draw  under  low  power 
showing  three  dimensions?  W^iat  is  the  shape  and  nature  of  the 
surfaces  of  the  alveoli?  Note  depressions  produced  by  connective 
tissue  fibers  supporting  the  alveoli. 

(d)  From  a  section  stained  with  orcein,  sketch  a  longitudinally  cut 
alveolar  duct  with  its  alveoli  showing  their  elastic  tissue  frame-work. 
Shape  of  alveoH  ?     How  are  the  arteries  of  the  section  characterized  ? 

(e)  From  a  thick  section  of  an  injected  specimen,  sketch  the  capillary 
system  of  an  alveolus.  Does  it  communicate  with  that  of  neigh- 
boring alveoli?  What  is  the  relative  distribution  of  the  arterial 
and  venous  capillaries  about  the  alveolus? 

(f)  From  the  drawings  made  in  b,  c,  d,  and  e,  reconstruct,  in  colors, 
half  an  alveolus  on  an  enlarged  scale,  showing  from  within,  the 
structures  in  position. 


LITERATURE.  10$ 

(g)  From  any  section  showing  it,  make  a  sketch  of  the  visceral  pleura, 
illustrating  the  nature  of  the  layers  of  which  it  is  composed. 

LITERATURE  ON  THE  RESPIRATORY  APPARATUS. 

Nose,  Larynx,  Trachea. 

DRASCH,  O.     Zur  Frage  der  Regeneration  des  Trachealepithels  mit  Riicksicht  auf  die 

Karyokinese  und  die  Bedeutung  der  Becherzellen.     Sitz.  d.  k.  Akad.  d.  Wissensch., 

Wien,  Bd.  S3,  p.  341,  1881. 
EXNER,   S.     Weitere  Studien  uber  die  Structur  der  Riechschleimhaut  bei  Wirbeltieren. 

Sitz.  d.  k.  Akad.  d.  Wissensch.,  Wien,  Bd.  65,  p.  7,  1872. 
FRANKEL,  B.     Zur  Histologie  der  Stimmbander.      Arch.  f.  path.  Anat.,  Bd.  118,  p.  370, 

18S9. 
FUCHS-WOLFRING,  S.     Ueber  den  feineren  Bau  der  Driisen  des  Kehlkopfes  und  der 

Luftrohre.     Arch.  f.  raik.  Anat.,  Bd.  52,  p.  735,  1898. 
\'AN  GEHUCHTEN,  A.     Contributions  a  1' etude  de  la  muqueuse  olfactive  chez  Ics  mam- 

miferes.     La  Cellule,  T.  6,  p.  395,  1890. 
HEYMANN,   R.     Beitrag  zur  Kenntnis   des  Epithels   und  der  Driisen  des  menschlichen 

Kehlkopfes  im  gesunden  und  kranken  Zustande.     Arch,  fur  path.  Anat.,  Bd.  118, 

p.  320,  1899. 
JOCOBSON,  A.     Zur  Lehre  vom  Bau  und  der  Function  des  Musculus  thyreoarytaenoideus 

beim  Menschen.     Arch.  f.  mik.  Anat.,  Bd.  29,  p.  617,  1887. 
KANTKACK,  A.  A.     Studien  liber  die  Histologie  der  Larynxschleimhaut.     Arch:  f.  path 

Anat.,  Bd.  118,  p.  137,  18S9. 
LEWIS,  D.  D.     The  Elastic  Tissue  of  the  Human  Larynx.     Am.  Jour,  of  Anat.,  Vol.  4,  No.  2, 

1905. 
MOST,    A.     Ueber  die  *  Lymphgefasse   und   Lymphdrlisen   des   Kehlkopfes.     Anat.    Anz., 

Bd.  15,  p.  387,  1899. 
SCHAFFER,  J.     Zur  Histologie,  Histogenese  und  phylogenetischen  Bedeutung  der  Epi- 
glottis.    Anat.  Hefte,  Abt.  i,  H.  loi  (Bd.  33,  H.  3),  p.  455,  1907. 
SCHMINCKE,  A.     Zur  Kenntnis  der  Drusen  der  menschlichen  regio  respiratoria.     Arch. 

f.  mik.  Anat.,  Bd.  61,  H.  2,  p.  233,  1902. 
SCLAVUNOS,    G.     Ueber  die   Ventrikularsacke   des   Kehlkopfes  beim  erwachsenen   und 

neugeborenen  Menschen  sowie  bei  einigen  Affen.     Anat.  Anz.,  Bd.  24,  No.  23-24, 

p.  652,  1904. 
SUDLER,  M.  T.     The   Development  of  the  Nose  and  of  the  Pharynx  and  its  Derivatives 

in  Man.     Am.  Jour,  of  Anat.,  Vol.  i,  No.  4,  1902. 

Lung. 

BREMER,  J.  L.     On  the  Origin  of  the  Pulmonary  Arteries  in  Mammals.     Am.  Jour,  of 

Anat.,  Vol.  i.  No.  2,  1902. 
BUDDE,  M.     Untersuchungen  iiber  die  sympathischen  Ganglien  in  der  Lunge  bei  Sauge- 

tieren  und  beim  menschlichen  Fotus.  Anat.  Hefte,  Abt.  i,  H.  72,  p.  211,  1904. 
COUNCILMANN,  W.  T.     The  Lobule  of  the  Lung  and  its  Relation  to  the  Lymphatics. 

Jour.  Boston  Soc.  of  Med.  Sc,  Vol.  4,  p.  165,  1900. 
DOGIEL,  A.  S.     Nervenendigungen  in  der  Pleura  des  Menschen  und  der  Saugetiere.     Arch. 

f.  mik.  Anat.,  Bd.  62,  p.  244,  1903. 
FLINT,  J.  M.     The  Development  of  the  Lungs.     Am.  Jour.  Anat.,  Vol.  6,  No.  i,  p.  i,  1906. 
GOETTE,  A.     Ueber  den  Ursprung  der-  Lungen.     Zool.   Jahrb.,  Abt.  f.  Anat.  u.   Ont., 

Bd.  21,  H.  I,  p.  141,  1905. 
KOTZENBERG,    W.     Zur   Entwicklung   der   Ringmuskelschicht   an   den   Bronchien    der 

Saugetiere.     Arch.  f.  mik.  Anat.,  Bd.  60,  H.  3,  p.  460,  1902. 
LINSER,  P.     Ueber  den  Bau  und  die  Entwdcklung  des  Eiastischen  Gewebes  in  der  Lunge. 

Anat.  Hefte,  Bd.  13,  p.  307,  1900. 
AIILLER,  W.  S.     The  Vascular  Supply  of  the  Pleura  Pulmonalis.     Am.  Jour.  Anat.,  \'ol.  7, 

No.  3,  p.  389,  1907. 
OPPEL,  A.     Atmungs-Apparat.     Ergebnisse  d.  Anat.  u.  Entwickelungsgesch.,   Bd.  13,  p. 

213'  1903-  .      . 

PLOSCHKO,  A.     Die  Nervenendigungen  und  der  Ganglien  der  Respirationsorgane.     Anat. 

Anz.,  Bd.  13,  p.  12,  1897. 
RETZIUS,  G.     Zur  Kenntnis  dor  Nervenendigungen   in   den    Lungen.     Biol.  Untersuch., 

N.  F.  5,  p.  41,  1893. 
ZUCKERKANDL,  E.     Ueber  die  Anastomosen  der  Venae  polmonales  mit  den  Bronchial- 

venen  und  mit  dem  mediastinalen  Venennetze.     Sitz.  d.  k.  Akad.  d.  Wissensch.,  Bd. 

54,  p.  no,  1882. 


V.  THE  URINO-GENITAL  SYSTEM. 

(tenth  paper.) 

A.  The  Urinary  Apparatus. 

1.  Macroscopic  appearances. 

(a)  Observe  the  organs  in  position  in  the  body  (hviman  or  dog)  and 
identify  the  following: 

(i)  The  kidneys  (renes),  their  position,  shape,  color  and  surfaces. 
The  hilus  renalis  and  its  relation  to  the  A.  renalis  and  V.  renalis 
arising  from  the  aorta  abdominalis  and  vena  cava  inferior. 
Whence  is  the  nerve  supply  derived  ? 

(2)  The  ureters.  How  do  they  differ  from  the  arteries  and  veins  in 
size  and  appearance,  and  in  their  connection  with  the  kidneys  ? 

(3)  The  bladder  (vesica  urinaria).  On  which  surface  do  the  ureters 
open  into  it?  Note  lig.  umbilicale  medium.  To  what  is  it 
attached?  Urethra  and  prostata,  where  situated?  Open  the 
bladder  and  note  plicae  mucosae,  orifices  of  the  ureters  and  orifice 
of  the  urethra  ? 

(b)  With  razor  divide  a  kidney  along  its  median  longitudinal  plane 
and  note  tunica  fibrosa,  substantia  corticalis,  substantia  meduUaris 
and  medullary  rays.  Observe  the  ureter  expanded  into  the  pelvis 
renales  with  its  calyces  majores  and  minores.  What  is  the  relation 
of  the  columnae  renales  to  the  general  supporting  tissue  of  the 
structures  in  the  hilus?  What  is  their  relation  to  the  pyramids 
and  calyces?  What  is  the  relation  of  the  pelvis  to  the  hilus? 
Make  a  sketch  of  the  section.  What  can  be  said  of  the  general 
distribution  of  the  blood-vessels?  Note  from  the  investigations 
cited  that  the  larger  blood-vessels  (arteriae  proprse  renales)  are 
separated  into  a  smaller  ventral  and  a  larger  dorsal  set. 

2.  Microscopic  structure  0}  the  kidneys. 

(a)  Sagittal  section  of  injected  specimen.     Under  low  power  draw  a 
segment  passing  from  hilus  to  tunica  fibrosa,  showing  the  following: 
(i)  Interlobar  and  arcuate  arteries  and  veins.     Where  are  they  sit- 
uated ?     Whence  are  they  derived  ?     In  what  direction  do  they 
run? 
(2)  The   capillary   system   of   the   substantia  medullaris.     Whence 
are  the  capillaries  derived  and  what  is  their  general  direction? 
What  is  the  nature  of  the  structure  between  them  ?     Note  arter- 
iole rectae. 

106 


THE    KIDNEYS,  I07 

(3)  Give  special  attention  to  the  capillary  system  of  the  substantia 
corticalis  opening  into  the  arteriae  and  venae  arcuatse.  Note 
arteriae  and  vensc  interlobulares.  Arising  from  the  interlobular 
arteries  observe  twigs  (vasa  afferentia)  which  break  up  to  form 
the  renal  glomeruli.  Arising  from  the  glomeruli  are  the  vasa 
efferentia  which  break  up  into  finer  capillaries  and,  as  arteriolae 
rectse,  those  nearest  the  medulla  contribute  to  the  capillary  system 
of  the  medulla  as  well  as  the  cortex.  Note  the  capsula  glomeruli 
(Bowman's  capsule).  What  is  its  nature?  With  what  is  it 
continuous?  What  constitutes  the  corpuscula  renis  (Malpighian 
corpuscle)  ?  Are  arteriole  rectae  spurite  to  be  observed  ?  Are 
there  arteries  entering  the  kidney  at  other  regions  than  the  hilus  ? 
If  so,  do  these  also  form  glomeruli?  Enumerate  the  divisions  of 
the  blood-supply  of  a  renal  lobule.  Of  what  are  the  cohimnje 
renales  (Bertini)  composed? 

(b)  Examine  under  dissecting  lens  sagittally  cut  pieces  of  a  kidney  of 
a  mammal  which  have  macerated  twenty-four  hours  in  30  per 
cent,  hydrochloric  acid  and  washed  in  running  water  one  hour. 
Choose  pieces  favorably  cut,  place  in  a  drop  of  glycerin  on  the 
slide  and  very  carefully  isolate  the  uriniferous  tubules  by  teasing. 
Cover  and  continue  the  isolation  by  gently  tapping  the  cover-glass. 
Identify  the  different  portions  of  the  tubules  to  be  seen  under  low 
power,  noting  especially  the  form  and  extent  of  the  glomeruli, 
the  convoluted  tubules,  the  loops  of  Henle  and  the  relation  of  the 
collecting  tubules  to  the  papillary  ducts. 

(c)  From  a  stained  section  of  a  human  kidney  passing  from  a  papilla 
to  the  tunica  fibrosa,  under  high  power  draw  small  areas  showing 
the  character  of  the  uriniferous, tubules  in  the  following  localities: 

(i)  A  small  area  of  the  substantia  corticales  illustrating  a  JNIalpighian 
corpuscle  with  glomerulus,  capsula  glomeruli  and  the  beginning 
of  the  uriniferous  tubule,  the  convoluted  character  of  the 
tubules  in  this  locality  and  the  varying  character  of  their  epithe- 
lium. How  does  the  epithelium  of  the  capsule  dift'er  from  that 
of  the  tubule?     What  can  be  said  of  the  supporting  tissue? 

(2)  A  small  area  from  the  apex  of  the  papilla,  projecting  into  the 
calyx,  showing  the  joining  of  the  collecting  tubules  to  form  the 
ductus  papillares  (ducts  of  Bellini).  How  does  the  epithelium 
here  differ  from  that  of  the  ducts  above?  Does  the  loop  of 
Henle  ever  extend  beyond  the  arcuate  vessels  into  the  medulla  ? 

(d)  From  the  various  studies  made,  reconstruct  a  renal  lobule  showing 
the  blood-vessels  (arterial  and  venous)  in  their  relation  to  the  urinif- 
erous tubules  and  the  course  of  a  tubule  from  the  corpusculum 
renalis,  showing  the  capsule,  proximal  convoluted  portion  (tubulus 
contortus),   the   ascending  and  descending  limbs  of  the  loop   of 


Id8  LABORATORY   GUIDE   FOR   HISTOLOGY. 

Henle  (tubuli  recti),  the  distal  convoluted  portion  continuous  into 
the  collecting  tubules,  and  the  papillary  duct. 
Read  carefully  the  descriptions  of  the  variations  in  the  epithelial 
lining  of  the  tubules,  noting  what  these  variations  signify, 
(e)  Make  a  small  sketch  showing  the  relative  thickness  and  nature  of 
the  tunica  fibrosa  of  the  kidney.     Does  it  contain  muscular  tissue  ? 

3.  The  ureters. 

Make  a  drawing  of  a  transverse  section  of  the  pelvic  part  of  a  human 
ureter  showing  in  detail  the  character  of  its  epithelial  lining,  the  folds  of 
the  mucosa  and  the  inter-relation  of  the  three  strata  of  the  tunica 
muscularis.  Examine  the  pelvis  of  the  kidney  (sections  above)  for  the 
transition  of  the  epithelium  of  the  papillary  ducts  into  the  variety 
found  in  the  ureter.  In  what  does  the  upper  or  abdominal  part  of 
the  ureter  differ  from  the  pelvic  part?  Explain  the  occurrence  or 
absence  of  a  tunica  serosa.     Are  there  glands  of  the  ureters  ? 

4.  The  bladder  {vesica  urinaria). 

(a)  Fresh,  macroscopic.  Review  the  position  of  the  bladder  in  the 
pelvic  cavity,  the  structures  adjacent  to  it,  the  locality  and  attach- 
ment of  the  medial  umbilical  ligament  (urachus),  the  localities  of 
entrance  of  the  ureters  and  exit  of  the  urethra,  and  the  color  and 
texture  of  the  organ.  Inflate  a  bladder  by  way  of  the  urethra, 
noting  its  remarkable  capability  of  distention.  What  constitutes 
the  trigonum  vesicae?  Open  the  bladder  and  note  evidence  of 
strikingly  loose  tunica  propria  allowing  numerous  folds  of  the 
mucosa  which  are  wholly  obliterated  by  distention  of  the  organ. 
What  is  the  origin  of  the  bladder  and  urethra  ?  Explain  the  attach- 
ment of  the  ureters  to  it. 

(b)  Microscopic.  Compare  a  stained  vertical  section  taken  from  the 
body  of  the  bladder  with  one  taken  from  the  trigonum  (fundus) 
near  the  urethral  orifice.  Draw  a  segment  from  either  section, 
showing  the  nature  of  the  epithelium  and  the  various  strata,  includ- 
ing the  tunica  serosa.  How  many  layers  of  cells  in  the  epithelium? 
Relative  size,  shape  and  number  of  nuclei  of  the  layer  of  superficial 
cells  ?  Actual  shape  of  the  cells  of  the  deeper  layers  ?  How  many 
muscle  strata  and  why  are  they  confused?  Why  are  the  three 
strata  of  the  tunica  muscularis  more  definitely  arranged  in  the 
trigonum  than  in  the  general  body  of  the  bladder?  Relative 
abundance  of  connective  tissue?  In  what  locaUty  only  are  glands 
of  the  bladder  to  be  found?  Nature  of  their  secretion?  Explain 
the  fact  that  the  epithelium  of  the  bladder  when  distended  consists 
of  fewer  layers  of  cells  and  of  cells  of  very  different  shape  as  com- 
pared  with  that  of  the  contracted  condition.     Look   for  lymph 


THE    MALE    GENITAL    APPARATUS.  IO9 

nodules  in  the  sections.  What  can  be  said  of  the  nerve-supply  of 
the  bladder?  Look  for  cells  of  small  sympathetic  ganglia  in  its 
wall.  Abundance  of  the  blood-supply?  Where  are  the  larger 
vessels  situated? 

5.  The  urethra  (jemale). 

The  male  urethra  will  be  studied  with  the  male  genital  organs.  Under 
low  power  draw  a  transverse  section  showing  the  folded  nature  of  the 
mucosa,  the  scant  supply  of  glands,  the  pecuHar  character  and  arrange- 
ment of  the  strata  of  the  tunica  muscularis,  and  the  thick  tela  sub- 
mucosa  pervaded  by  numerous  blood-vessels,  many  of  which  are 
sinusoidal  venous  channels  giving  resemblance  to  the  erectile  tissue  com- 
prising the  corpus  cavernosum  urethrse  of  the  male.  How  does  the 
epithelium  of  the  external  (vaginal)  orifice  differ  from  that  of  other 
parts?  Which  of  the  muscle  strata  is  concerned  and  what  variety  of 
muscle  predominates  in  the  formation  of  the  M.  sphincter  urethrae  ? 

B.  The  Male  Genital  Apparatus  {organa  genitalia  virilia). 

I.  Macroscopic  relations. 

(a)  Study  the  arrangement  of  the  component  parts  of  the  human 
genital  apparatus  in  position  either  from  atlases  or  in  the  subject 
in  the  dissecting  room,  noting  the  relations  to  each  other  of  the 
following:  scrotum;  tunica  dartos;  M.  cremaster;  tunica  vaginalis 
communis;  plexus  pampiniformis;  tunica  vaginalis  propria;  testis 
with  its  tunica  albuginea;  epididymis  with  caput,  corpus  and  cauda; 
ductus  deferens  with  its  ampulla,  vesicula  seminalis  and  ductus 
e jaculatorius ;  prostate  gland,  and  penis  with  its  glans,  crus  and 
bulbus  urethra?.  From  dissections,  or  illustrations,  trace  ductus 
ejaculatorius  through  prostata  into  urethra,  noting  colliculus 
seminalis  and  utriculus  prostaticus.  Of  the  urethra,  identify  pars 
prostatica,  pars  membranacea,  pars  cavernosa  and  fossa  navicularis. 
Note  the  relation  of  the  glandula  bulbourethralis  (Cowper's  gland) 
to  the  corpus  cavernosum  urethrse  (corpus  spongiosum),  and  note 
the  arrangement  and  consistency  of  the  corpora  cavernosa  penis. 

(b)  With  razor  split  the  testis  and  epididymis  (human  or  dog)  sagitally 
and  under  dissecting  lens  sketch  the  surface  exposed  showing  the 
following:  tunica  albuginea;  mediastinum  (body  of  Highmore); 
the  septa  dividing  the  testis  into  lobules;  the  tubular  structure  of 
the  lobules;  the  rete  testis  and  the  epididymis.  The  ductuli 
efferentes  arise  from  the  rete  and  join  the  single  but  greatly  con- 
torted ductus  epididymis  which  is  continuous  into  the  ductus 
deferens  at  its  emergence  from  the  cauda  of  the  epididymis.  From 
the  sections  to  be  used  in  3  and  4  below,  note  the  abundance,variety 
and  arrangement  of  the  supporting  tissue  of  the  parts. 


no  LABORATORY    GUIDE    FOR   HISTOLOGY. 

2.  Spermatosomes  {spermatozoa). 

(a)  Fresh  seminal  fluid^  may  be  obtained  most  favorable  for  study 
(less  diluted  and  containing  less  mucus)  from  the  epididymis 
of  the  dog,  the  spermatozomes  of  which  animal  closely  resemble  the 
human.  With  scissors  the  fresh  epididymis  should  be  snipped  into 
bits  into  a  watch  glass  of  normal  salt  solution.  Mount  a  drop  of  the 
salt  solution  and  examine  under  high  power.  Note  that  the 
motility  of  the  organisms  increases  after  the  first  ten  minutes  in 
the  salt  solution  and  that  the  movement  of  those  with  straight 
tail-pieces  (mature)  is  more  vigorous  than  that  of  those  bent  at  the 
junction  of  the  middle-piece  and  tail-piece.  Some  of  those  bent 
at  first  become  straight  after  a  few  minutes. 

(b)  At  the  time  the  above  material  is  obtained,  make  a  cover-glass, 
smear  preparation  of  the  seminal  fluid,  fix  one  hour  in  Van  Gehuch- 
ten's  fluid,  wash  ten  minutes,  first  in  95  per  cent,  and  then  in  70 
per  cent,  alcohol,  stain  with  hematoxylin  and  eosin,  dehydrate, 
clear  and  mount  in  balsam.  Draw  one  or  two  spermatosomes 
under  high  power,  identifying  the  four  parts.  Is  there  a  head  cap 
or  lance  ?  Undulating  membrane  ?  Compare  with  human  sper- 
matosome. 

3.  Spermatogenesis. — Study  the  process  from  thin,  stained  sections 
involving  lobules  of  human  testis  and  that  of  the  rat.  From  the  latter 
draw  segments  of  tubuli  contorti  seminiferi  showing  four  or  five  stages 
of  sperm'atogenesis,  including  in  each  drawing  sustentacular  cells, 
spermatogonia,  spermatocytes,  spermatids  and  further  developed 
spermatosomes.  In  which  cells  are  evidences  of  Karyokinesis  ?  On  a 
larger  scale,  illustrate  the  internal  morphology  of  a*  spermatid.  State 
the  disposition  of  its  constituent  elements  in  the  formation  of  the  mature 
spermatosome.  In  drawing  the  segments  of  the  tubules,  include  the 
membrana  propria  and  some  of  the  interstitial  connective  tissue. 

4.  Under  high  power,  draw  a  few  of  the  interstitial  cells  0}  Leydig  from 
sections  of  the  human  testis.  Varieties  of  the  cells?  Their  behavior 
during  the  growth  and  functioning  of  the  gland  ?     Their  significance  ? 

5.  From  sections  involving  the  human  mediastinum  testis,  epididymis  and 
ductus  deferens,  draw  and  compare  transverse  sections  of  the  different 
ducts,  especiaUy  noting  changes  in  the  epithelium  of  the  tubuli  recti, 
rete,  ductus  efferens,  ductus  epedidymis  and  ductus  deferens.  Where  do  the 
cilia  begin?  The  three  strata  of  muscle?  Compare  ductus  deferens 
with  ureter.  Also  make  a  small  drawing  illustrating  the  structure  of 
the  vesicula  seminalis  and  compare  its  structure  with  that  of  the  ampulla 
ductus  deferentis.     Cilia  ?     Variations  in  tunica  muscularis  ? 

6.  Prostata. — Sketch  a  segment  of  the  gland  (human)  from  a  section 
transverse  to  the  urethra,  showing  the  dense  muscular  and  connective 


THE    FEMALE    GENITAL    APPARATUS.  Ill 

tissue  investments  and  the  radiating  systems  of  compound  branched 
alveoli  forming  the  lobules.  What  is  the  shape  of  the  lobules  ?  Chemi- 
cal nature  of  secretion  ?  How  does  the  succus  prostaticus  pass  into  the 
urethra?  Significance  of  the  utriculus  prostaticus?  What  variety  of 
epithelium  lines  the  prostatic  portion  of  the  urethra?  What  is  the 
relation  of  the  muscle  of  the  prostate  to  the  M.  sphincter  urethrae? 
In  dilated  portions  of  the  ducts  and  alveoli  of  the  gland,  look  for  colloid 
concretions  (prostatic  stones).  What  is  the  origin  and  pathological 
significance  of  these?  What  of  the  abundance  of  the  blood-supply  of 
the  prostate  and  the  nature  of  its  nerve-supply  ? 

7.  Penis  and  urethra. 

(a)  Sketch  a  transverse  section  through  the  cavernous  region  and  a 
longitudinal  section  involving  the  glans  penis  (human  or  monkey). 
Especially  note  the  corpora  cavernosa  penis  with  their  tunica 
albuginea,  their  septum  penis  and  the  character  of  their  structure; 
the  urethra  and  the  character  of  its  epithelium  and  glands;  the 
corpus  cavernosum  urethras  (corpus  spongiosum)  with  its  tunica 
albuginea,  the  distribution  of  its  muscle,  its  arteries,  and  the 
abundance  and  structure  of  its  cavernous  sinuses;  the  fascia  penis 
with  its  nerve  trunks;  the  x\a.  and  V.  dorsales  and  A.  profunda, 
and  the  integument.  Why  are  the  corpora  cavernosa  so  named  ? 
From  which  of  them  is  the  glans  penis  derived?  Divide  the 
structure  of  the  corpus  cavernosum  urethra  into  tunica  propria 
mucosae,  tela  submucosa  and  tunica  muscularis.  How  and  why 
does  the  epithelium  of  the  navicular  portion  of  the  urethra  (glans) 
differ  from  that  of  the  other  regions  ?  How  many  varieties  of  glands 
are  to  be  found  in  the  section  of  the  glans  penis?  Look  for  cor- 
pusculated  nerve  terminations,  especially  in  the  glans.  Sections  of 
nerve  twigs  in  the  corpora  cavernosa  ?  Under  high  power,  draw  a 
small  area,  illustrating  the  detailed  structure  of  the  corpora 
cavernosa. 

(b)  Draw  a  segment  of  a  section  of  a  bulbourethral  (Cowper's)  gland 
showing  the  character  of  the  capsule,  the  secretory  alveoli  and 
ducts.  Note  that  the  larger  of  the  latter  have  muscle  in  their 
tunics.  Look  for  and  determine  the  significance  of  both  striated 
and  smooth  muscle-fibers  in  the  periphery  of  the  section.  What  is 
the  appearance  and  chemical  nature  of  the  secretion  of  the  gland? 

C.  The  Female  Genital  Apparatus  {orgaiia  genitalia  muliebria). 

I.  Macroscopic. 

(a)  From  atlases  or  in  their  position  in  the  body  (human  or  dog), 
identify  the  following  structures:  ovarium  with  its  free  margin  and 
ligamentum    proprium;    tuba    uterina    (Fallopian   tube)    with    its 


112  LABORATORY   GUIDE   POR   HISTOLOGY. 

fimbria,  infundibulum,  ampulla,  and  isthmus;  uterus  with  its 
fundus,  cer\ix,  and  external  orifice  (posterior  and  inferior  labia). 
Note  the  relation  of  the  latter  to  the  vagina.  How  does  the  uterus 
of  the  dog  difi'er  from  the  human  ? 

(b)  With  razor,  di\dde  the  ovarium  (dog  or  hog)  and,  with  the  aid  of 
dissecting  lens,  note  tunica  albuginea  and  stroma  ovarii;  corpora 
lutea  and  foUiculi  vesiculosi  (Graafian  follicles). 

(c)  From  a  demonstration  specimen  of  the  human  uterus  divided 
longitudinally,  identify  ostea  of  tubae  uterinae,  cavum  uteri,  canalis 

^cervicalis,  with  plicae  palmatae,  and  the  labia  of  the  orifice.     What 
can  be  said  of  the  walls  of  the  uterus?     Sketch. 

2.  Microscopic  structure. 

(a)  The  ovarium  (ovary). 

(i)  From  a  stained  section  of  an  ovary  of  a  very  young  animal  or 
fetus,  draw  under  low  power  a  small   area   showing  germinal 
epithelium,    primordial  ova  (sexual  cells),  follicles  and  stroma. 
Whence  are  the  ova  derived  ?     Show  "  egg  tubes"  or  ''  egg  nests." 
Is  there  any  muscular  tissue  in  the  section  ? 
(2)  Ovogenesis. — From   stained    sections    of    adult    ovaries,    make 
drawings  under  high  power  showing  the  following  developmental 
stages  of  the  follicles: 
(i)  Primary  follicle  or  oocyte  of  the  first  order  (foUiculus  oophori 
primarii)  showing  oocyte  enclosed  by  a  single  layer  of  flattened 
or  cubical  follicular  cells  and  surrounded  by  loosely  arranged 
stroma  ovarii, 
(ii)  A  follicle  showing  the  beginning  of  the  zone  of  growth,  i.  e. 
a  larger  ovum  (oocyte)  containing  yolk  granules  (deutoplasm) 
and  a  germinative  vesicle  (enlarged  nucleus)  and  enclosed  by 
a  zona   pellucida   surrounded  by  high  cylindrical,   radiating 
follicular  cells  with -the  immediately  surrounding  stroma  com- 
pressed into  a  theca  folliculi. 
(iii)  A  more  advanced  stage  showing  further  enlarged  ovum  with  a 
more  distinct  zona  pellucida  surrounded  by  a  solid  mass  of 
stratified,  radiating  follicular  cells  forming  the  corona  radiata, 
and  a  further  developed  theca  folliculi.     What  is  the  "  germinal 
spot?" 
(iv)  A  greatly  enlarged  follicle  showing  the  ovum  projecting  into 
an  antrum  folliculi  but  still  surrounded  by  a  cumulus  of  the 
corona  radiata  (discus  proligerus)  and  attached  to  the  mem- 
brana  granulosa,  or  remains  of  the  corona  radiatai,  adhering  to 
the  theca.     Note  now,  two  tunics  of  the  theca.     What  is  the 
nature  and  the  origin  of  the  substance  which  fills  the  antrum  ? 


THE    UTERUS.  II3 

Derivation  of  the  zona  pellucida  ?  How  are  oocytes  of  the  second 
order  produced,  and  what  further  changes  must  occur  before 
the  maturation  of  the  ovum  is  complete?  Give  a  mechanical 
explanation  of  the  extrusion  of  the  ovum.  Compare  the 
development  and  maturation  of  the  ovum  with  that  of  the 
spermatosome. 

(3*)  Study  a  corpus  luteum  in  section.  What  is  its  relation  to  the 
ruptured  follicle  and  the  corpus  hemorrhagicum  ?  Whence  are 
the  structures  composing  it  derived?  Draw  a  few  lutein  cells 
with  the  supporting  tissue  about  them,  showing  their  structure 
in  detail.  What  is  the  process  by  which  the  corpus  luteum  dis- 
appears and  what  is  the  origin,  structure  and  fate  of  the  corpus 
albicans  ? 

(b)  Tuba  uterina  (Fallopian  tube). 

Study  and  compare  a  transverse  section  from  the  isthmus  with  one 
passing  through  the  ampulla.  Why  is  the  tunica  serosa  incom- 
plete ?  Note  evidence  that  the  extensive,  compound  foldings  of  the 
mucosa  of  the  ampulla  are  permanent  folds  while  the  fewer  and 
simpler  folds  in  the  isthmus  are  not  necessarily  permanent.  The 
tunica  propria  is  vascular  and  extends  into  the  folds  in  all  regions. 
In  what  tunic  are  the  larger  blood-vessels  situated  ?  In  what  region 
does  the  tunica  muscularis  consist  of  three  strata  and  what  are  the 
directions  of  these?  Which  of  these  strata  persists  throughout 
the  tube  and  thus  is  present  in  the  infundibulum  ?  Can  the  inner- 
most stratum  be  considered  a  muscularis  mucosae  ?  Note  the 
variety  of  the  epithelium  in  both  sections.  Are  all  the  cells  ciliated  ? 
Does  the  tube  possess  glands  in  any  region?  Make  a  careful 
drawing  of  the  section  of  the  isthmus.  Compare  it  with  the  ductus 
deferens  and  with  the  ureter. 

(c)  The  uterus  (non-pregnant). 

Draw  a  narrow  strip  through  the  wall  from  a  section  through  either 
•  the  body  or  the  cervix  of  the  uterus.  Note  the  great  thickness  and 
vascularity  of  the  mucosa  and  numerous  outfoldings  of  its  epithelium 
forming  the  so-called  uterine  glands.  What  are  the  reasons  for  not 
considering  the  majority  of  these  foldings  as  true  glands?  In  the 
cervix  look  for  evidence  of  mucus  producing  cells  in  the  epithelium 
of  the  folds.  Where  are  these  true  (cervical)  glands  most  active  ? 
Explain  the  variable  occurrence  of  cilia.  How  many  strata  com- 
prise the  tunica  muscularis  and  in  what  region  are  these  strata  most 
distinct?  Abundance  of  elastic  tissue?  State  the  changes  in  the 
entire  wall  which  occur  during  pregnancy. 


114  LABORATORY    GUIDE    FOR    HISTOLOGY. 

(d)  The  vagina. 

Draw  a  strip  through  a  transverse  section  of  the  middle  portion  of 
the  vagina,  showing  its  thick  epithelium  thrown  into  coarse  rugae 
and  resting  upon  papillae  occupied  by  a  delicate  tunica  propria, 
and  including  the  muscular  and  cavernous  tissues  of  its  wall.  Glands 
are  absent  in  this  region.  What  is  the  character  of  the  major  and 
minor  vestibular  glands?  To  what  gland  in  the  male  do  the 
major  vestibular  (Bartholin's)  glands  correspond?  Look  for 
evidences  of  the  ganglionated  nerve  plexuses  in  the  fibrous  tunic. 

(e)  The  Mammary  Gland  (Mamma). — One  of  the  glands  of  the  skin, 
(i)  From  a  section  passing  vertically  through  the  mammilla  (nipple) 

and  involving  the  structures  beneath,  make  a  drawing  showing 
general  arrangement  of  component  tissues,  especially  the  ductus 
lactiferi  (mammary  ducts),  sinus  lactiferi,  lobi  and  lobuli  mammae, 
and  finally,  the  alveoli.  In  what  does  the  epidermis  covering 
the  mammilla  differ  from  that  of  other  regions  ?  What  are  the 
glandulae  alveolares  (Montgomery's  glands)  ?  Explain  the 
presence  and  position  of  muscular  tissue  in  the  corium.  Note 
the  abundance  of  paniculus  adiposus. 
(2)  Under  high  power,  sketch  one  or  two  alveoli  from  a  section  of  any 
mammillian  mammary  gland  in  the  process  of  lactation.  Show 
in  detail  the  changes  which  the  gland  cells  undergo  in  the  pro- 
duction of  milk.  Look  for  colostrum  corpuscles.  During  what 
stage  of  lactation  are  they  most  abundant?  Explain  their 
occurrence.  Draw  one  or  two  separately.  Read  up  the  structure 
of  mammary  glands  of  the  male. 

LITERATURE  ON  THE  URINO-GENITAL  SYSTEM. 
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LITERATURE.  II 5 

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THE  CENTRAL  NERVOUS  SYSTEM. 

(Portions  of  the  first  part  of  this  chapter  are  modifications  of  certain  para- 
graphs in  Chapter  XX  of  Hardesty's  Neiirological  Technic,  The  University  of 
Chicago  Press,  1902). 

(eleventh  paper.) 
I.  THE  SPINAL  CORD  (medulla  spinaHs). 

A.  Macroscopic  Study. 

1.  Peripheral  Connections. — ^Fetal  pig  of  25  to  30  centimeters. 

(a)  E^iscerate  the  fetus  through  a  median  ventral  incision  and  wash 
out  the  body  ca\-ity.  Note  the  spinal  nerves  arranged  at 
intervals  (segments)  and  passing  from  the  dorsal  raid-line  (axis) 
of  the  body.  Carefully  observe  the  sympathetic  trunk  with  the 
ganglia  of  this  trunk,  the  gangliated  cord,  extending  along  either 
side  of  the  vertebral  column.  By  gently  dissecting,  trace  rami 
communicantes  from  the  ganglia  of  the  sympathetic  trunk  into  the 
body  wall  to  connect  with  the  trunks  of  the  spinal  nerves.  Note 
other  branches  radiating  from  the  gangHa,  many  of  which  go  to 
form  the  aortic  plexus;  others,  broken,  pass  to  the  more  distal 
sympathetic  ganglia,  removed  with  the  \'iscera;  others  cross  the 
vertebral  column  and  connect  with  the  ganglia  of  the  opposite  side 
(commissural  branches).  Note  that  the  spinal  nerves  of  the 
thoracic  or  mid-region  of  the  body  pass  singly  to  their  distribution 
to  the  tissues,  while  those  of  the  arm  region  and  those  of  the  caudal 
end  of  the  axis  unite  with  each  other  to  form  the  brachial  and 
lumbar  plexuses  respectively.  Sketch  one  or  two  of  the  spinal 
nerves  of  the  thoracic  region  in  position,  showing  the  corresponding 
portions  of  the  sympathetic  trunk  and  ganglia  with  their  several 
connecting  branches. 

2.  Appearances  of  the  spinal  cord  in  situ.  In  addition  to  the  fetal 
pig  in  the  hands  of  each  student,  one  or  two  formalin  preserved,  demon- 
stration specimens  of  adult  human  spinal  cords  are  displayed  for  com- 
parison and  reference. 

(a)  Dissection,  pig.  Place  the  fetus,  dorsal  aspect  upward,  with 
limbs  extended.  Make  an  incision  in  the  dorsal  mid-line  along  the 
entire  length  of  the  body  including  the  head  and  neck,  and  remove 
the  skin,  muscles  and  other  soft  parts  adjacent  to  the  vertebral 
column,  working  laterally  from  the  midline.  Then,  with  small 
119 


I20  LABORATORY    GUIDE    FOR   HISTOLOGY. 

bone  forceps  or  strong  scissors,  expose  the  spinal  cord  by  clipping 
each  arcus  vertebrje  (process)  as  close  to  the  intervertebral  foramen 
as  possible,  taking  care  to  avoid  crushing  or  tearing  the  structures 
l}dng  within  the  vertebral  canal.  The  spinal  cord,  enclosed  in  its 
dura  mater,  being  thus  exposed,  carefully  expose  the  spinal  nerves 
of  one  side,  dissecting  sufl&ciently  to  show  the  spinal  ganglia  and 
the  adjoining  portions  of  the  nerve  trunks. 

Also  expose  the  encephalon  by  removing  the  superior  cranial  bones, 
taking  care  to  leave  intact  the  dura  mater  encephali. 

(b)  Sketch  the  dorsal  aspect  of  the  central  nervous  system  in  situ  and 
enclosed  by  the  meninges.  Identify  the  following  divisions: 
cerebrum,  cerebellum  and  medulla  oblongata  with  the  fourth 
ventricle  and  its  calamus  scriptoris;  the  spinal  cord,  its  general 
shape  and  extent,  its  cervical  portion  with  cervical  enlargement 
(intumescentia)  and  8  pairs  of  cervical  nerves  attached;  its  thoracic 
portion  with  12  pairs  of  thoracic  nerves;  its  lumbar  portion  with  the 
lumbar  enlargement  and  5  pairs  of  lumbar  nerves,  and  its  sacral 
portion  with  5  pairs  of  sacral  and  one  pair  of  coccygeal  nerves. 
Compare  with  other  specimens  in  the  class  for  variations  in  the 
number  of  spinal  nerves. 

(c)  Meninges  of  the  spinal  cord.  Carefully  sUt  the  spinal  dura  mater 
down  the  dorsal  mid-line.  Does  it  vary  in  thickness?  Compare 
with  human.  Lift  aside  the  dura  and  identify  the  spinal  arach- 
noidea  (very  scant  in  the  fetus).  In  this  a  definite  membrane? 
Subdural  cavity  and  denticulte  Hgaments?  What  is  the  ofhce  of 
the  subarachnoideal  septum?  Identify  the  spinal  pia  mater. 
How  does  it  differ  from  the  other  two  meninges  in  thickness  and  in 
its  relation  to  the  spinal  cord  ?  Make  a  sketch  showing  the  relations 
of  the  three  membranes  to  each  other  and  to  the  spinal  cord  as  seen 
in  the  human  specimen. 

Leaving  the  nervous  system  and  its  meninges  in  situ,  place  the 
entire  specimen  into  several  times  its  volume  of  5  per  cent,  formalin 
for  12  hours  or  more. 

(d)  Wash  in  water  and  then  expose  the  spinal  .cord  proper  along  its 
entire  length  by  pinning  aside  the  dura  mater.  Note  that  in  the 
fetus  the  cord  occupies  practically  the  entire  vertebral  canal. 
Compare  with  the  adult  human.  Observe  that  each  spinal  nerve 
is  connected  with  the  spinal  cord  by  a  dorsal  or  posterior  root  and  a 
ventral  or  anterior  root.  In  which  region  are  the  roots  shortest 
and  attached  most  nearly  at  right  angles  to  the  cord?  In  which 
are  they  longest?  What  constitutes  the  cauda  equina?  Note 
that  throughout,  each  root,  upon  approaching  the  cord,  is  divided 
into  numerous  radicular  filaments.  Examine  the  sacral  extremity 
of  the  spinal  cord,  identifying  the  conus  medullaris  and  the  filum 


SECTIONS    OF    SPINAL    CORD.  121 

terminale.  How  far  does  the  latter  extend?  Is  it  nervous? 
Explain  the  fact  that  in  the  adult  the  spinal  cord  does  not  extend 
the  entire  length  of  the  vertebral  canal,  and  explain  the  increasing 
Jength  of  the  spinal  nerve-roots  in  passing  candad,  and  the  resulting 
cauda  equina.  From  the  human  specimen,  hardened  in  formalin, 
sketch  the  region  of  the  cauda  equina,  showing  the  lumbar  enlarge- 
ment, conus  meduUare  and  filum  terminale, 

3.  Sever  the  spinal  cord  of  the  pig  from  the  encephalon  at  the  level  of 
the  calamus  scriptorius  and  carefully  remove  it  from  the  vertebral 
canal,  leaving  attached  one  or  two  of  the  spinal  nerves  of  each  of  the 
three  regions.  Then  remove  the  spinal  dura  mater  and  arachnoidea 
and  compare  in  detail  the  ventral  aspect  of  the  spinal  cord  with  the 
dorsal  aspect.  Are  the  ventral  roots  thicker  than  the  dorsal?  Which 
are  attached  to  the  cord  nearer  the  mid-line?  WTiich  set  of  the  roots 
is  more  finely  divided  into  radicular  filaments?  Note  the  anterior 
spinal  artery.  Are  there  posterior  spinal  arteries?  Note  the  evident 
ventral  or  anterior  median  fissure  and  the  line  indicating  the  dorsal  or 
posterior  septum.  Determine  the  boundaries  of  the  posterior  funiculus, 
the  lateral  funiculus  and  the  anterior  funiculus.  Sever  the  head  of  the 
fetus  from  the  body  and  return  the  head  to  the  formalin  solution  for 
use  in  the  study  of  the  sense-organs. 

4.  The  composition  of  the  spinal  nerves.  Note  that  the  trunk  of  each 
nerve  is  formed  by  the  fusion  of  its  dorsal  and  ventral  roots  in  the 
neighborhood  of  its  spinal  ganglion.  Detach  a  cervical  or  a  thoracic 
nerve  from  the  spinal  cord,  carefully  clean  it  off  under  the  dissecting 
microscope,  and  sketch  it  from  its  lateral  aspect,  showing  the  relative 
size  of  the  two  roots,  their  fusion  and  relation  to  the  spinal  ganglion, 
the  relative  size  and  direction  of  the  anterior  and  posterior  primary 
divisions  of  the  nerve  trunk  and  the  connection  of  the  ramus  com- 
municans.  Tease  a  root  and  then  the  spinal  ganglion.  Differences 
between  them?  Which  root  is  more  intimately  associated  with  the 
ganglion  ?     Functions  of  the  roots  ? 

5.  Sections  of  the  spinal  cord,  unstained. 

With  a  razor  or  sharp  scalpel,  remove  a  transverse  section  from  the  level 
of  the  seventh  cervical  segment.  Keeping  its  orientation  in  mind,  ex- 
amine one  of  the  cut  surfaces  for  the  following:  the  bilateral  symmetry 
of  the  section;  the  posterior  septum  and  the  anterior  median  fissure; 
the  shape  of  the  column  of  gray  substance  and  the  variations  in  the 
thickness  of  the  mantle  of  white  substance  surrounding  it;  the  dorsal 
and  ventral  horns  (columns),  the  gray  commissure,  and  the  relation  of 
the  respective  nerve-roots  to  the  horns.  What  constitutes  the  difference 
between  white  and  gray  substance?  WTiat  is  the  reticular  formation? 
What  is  the  relation  of  the  tissues  of  the  pia  mater  to  the  section? 
Compare  the  section  with  similar  sections  through  the  thoracic  and 


122  LABORATORY    GUIDE    FOR    HISTOLOGY. 

lumbar  regions.  Were  the  mantle  of  white  substance  removed  from 
the  entire  spinal  cord,  of  what  shape  would  the  column  of  gray  sub- 
stance appear  ? 

B.  Microscopic     Adult  human.     Stained  sections. 

1.  Review  the  study  of  the  neurones  of  the  spinal  cord  made  when  con- 
sidering the  histology  of  the  nervous  system. 

(a)  Their  external  morphology,  variations  in  size,  significance  and  dis- 
tinguishing features  of  the  axons  and  dendrites,  and  the  number 
of  types  of  neurones  represented  in  the  spinal  cord  and  spinal 
gangha. 

(b)  Their  internal  morphology,  the  anatomy  and  relative  size  of  the 
nucleus,  the  occurrence,  origin  and  significance  of  the  tigroid  masses, 
and  the  variations,  distribution  and  significance  of  the  neuro- 
fibrillce. 

(c)  The  presence,  extent  and  structure  of  the  medullary  sheaths. 

(d)  The  forms  of  nerve  termination,  both  central  and  peripheral,  and 
the  arrangements  and  relationships  whereby  the  grouping  and 
chaining  together  of  neurones  is  accomplished.  What  is  the 
significance  of  the  "intermediate  neurone?"  Differences  btween 
centrifugal  and  centripetal  neurones? 

2.  Review  carefully  the  architecture  of  the  spinal  ganglion.  What 
characterizes  the  chief  type  of  cell-body  of  the  neurone  contained  in  the 
ganglion?  Character  and  functional  significance  of  the  Dogiel  spinal 
ganglion  "neurone  of  Type  II ? "  Significance  of  the  two  other  types  of 
neurones  represented?  The  occurrence  and  explanation  of  the  excess 
of  nerve-fibres  of  the  peripheral  side  of  the  spinal  ganglion  as  compared 
with  the  sum  of  the  fibres  contained  in  the  dorsal  and  ventral  roots? 
What  is  the  behavior  of  the  fibres  of  the  dorsal  roots  upon  their  entering 
the  spinal  cord? 

3.  Under  a  magnification  of  7  diameters,  make  a  careful  drawing  of  a 
transverse  section  taken  from  the  sixth  cervical  segment  (cervical 
enlargement)  of  the  human  spinal  cord,  stained  by  the  Weigert 
method  for  the  medullary  sheaths  and  lightly  counterstained  with 
Upson's  carmin  for  the  cell-bodies  of  the  neurones.  Identify  and  show 
the  following: 

(a)  The  meninges;  the  anterior  and  posterior  spinal  arteries  and  veins; 
the  posterior  median  sulcus,  posterior  septum,  and  anterior  median 
fissure;  the  postero-lateral,  antero-lateral,  postero-intermediate  and 
antero-intermediate  sulci  and  the  septa  indicated  by  them.  Which 
of  the  sulci  are  associated  with  the  entrance  and  exit  of  the  fibers 
of  the  dorsal  and  ventral  roots  ?  Note  the  septum  subarachnoideale. 
How  is  the  subarachnoid  space  divided?  Relation  of  the  anterior 
spinal  artery  to  the  ventral  fissure  and  the  "linea  splendens?" 


THE    WHITE    SUBSTANCE.  1 23 

(b)  The  gray  substance;  the  dorsal  horn  (posterior  column)  with  its 
apex,  caput  and  cervix;  the  reticular  formation;  the  ventral  horn 
(anterior  column),  lateral  horn,  and  gray  commissure  with  the 
central  canal,  central  gray  substance,  and  ventral  (anterior)  white 
commissure.  State  the  origin  and  distribution  of  the  axones  which 
constitute  the  ventral  white  commissure?  What  is  the  relation  of 
the  dorsal  horn  to  the  fibres  of  the  dorsal  roots?  Of  the  ventral 
and  lateral  horns  to  the  fibres  of  the  ventral  roots?  What  is  the 
structure  and  appearance  of  the  gelatinous  substance  of  Rolando? 
Note  the  distribution  of  the  larger  cell-bodies  in  the  ventral  gray 
substance  and  divide  them  into — 

(i)  A  ventral  group  with  a  ventro-lateral  and  a  ventro-medial  portion. 

(2)  A  dorso-medial  group. 

(3)  A  lateral  group  occupying  the  lateral  horn,  and  sometimes 
separated  into  a  dorso-lateral  and  a  ventro-lateral  portion;  and 

(4)  An  intermediate  group,  occupying  the  mid-dorsal  portion  of  the 
ventral  honi.  State  the  probable  distribution  of  the  axones 
arising  from  each  of  these  groups  of  cell-bodies. 

How  do  the  cell-bodies  of  the  dorsal  horn  differ  from  those  of  the 
ventral  gray  substance  ?  \Vhat  is  the  general  functional  signifi- 
cance of  the  smaller  cell-bodies  scattered  throughout  the  entire 
gray  substance  ? 

(c)  The  white  substance.  Note  that  the  axons  of  the  white  substance 
comprise  four  general  neurone  systems:  (i),  the  cerebro -spinal 
system  ascending  and  descending;  (2)  the  cerebello-spinal  system, 
ascending  and  descending;  (3),  the  commissural  fibers  which  cross 
the  mid-line  to  connect  the  two  sides,  and  (4),  the  association 
fibers  which  course  varying  distances  both  upward  and  down- 
ward to  connect  diff'erent  levels  of  the  gray  substance  and  which 
compose  the  fasciculi  proprii  of  the  spinal  cord.  Give  the  bound- 
aries of  the  three  funiculi  into  which  the  white  substance  is 
divided  and  ascertain  the  position,  approximate  shape,  relative  size, 
origin  and  functional  direction  of  the  fasciculi  composing  each 
funiculus,  as  follows: 

(i)  The  posterior  funiculus,  consisting  of  the  fasciculus  gracilis 
(Goll's  column),  the  fasciculus  cuneatus  (Burdach's  column), 
the  comma-shaped  fasciculus,  the  dorsal  fasciculus  proprius, 
and  the  comu-commissural  tract. 

(2)  The  lateral  funiculus,  consisting  of  the  lateral  cerebro-spinal 
fasciculus  (crossed  pyramidal  tract),  the  ascending  cerebello- 
spinal fasciculus  (direct  cerebellar  tract),  the  superficial  ventro- 
lateral fasciculus  (Gower's  tract),  the  olivary  fasciculus  (Helwig's 
bundle),  the  mixed  intermediate  fasciculus,  the  marginal  fascicu- 
lus of  Lissauer,  and  the  lateral  fasciculus  proprius. 


124  LABORATORY    GUIDE    FOR   HISTOLOGY. 

(3)  The  anterior  funiculus,  consisting  of  the  ventral  cerebro-spinal 
fasciculus  (direct  pyramidal  tract),  the  anterior  marginal  fascic- 
ulus, the  sulco-marginal   fasciculus,  the  ventral  fasciculus  pro- 
prius,  and  the  commissural  bundle. 
Attach  the  names  to  all  structures  represented  in  the  drawing. 

4.  Under  the  same  magnification,  make  careful  drawings  of  similarly 
treated  sections  taken: 

(a)  From  the  first  cervical  segment. 

(b)  From  the  eighth  thoracic  segment. 

(c)  From  the  middle  of  the  lumbar  enlargement. 

(d)  From  the  conus  medullaris. 

What  is  the  position  and  longitudinal  extent  of  the  nucleus 
dorsalis  (Clark's  column)  ?  To  what  fibres  do  its  cell-bodies  give 
origin?  In  which  segments  is  it  thickest?  What  is  the  position, 
significance  and  extent  of  "  Stilling's  nucleus?"  Attach  the  names 
to  all  structures  not  found  in  the  first  section  or  which  are  greatly 
modified. 

5.  Lay  the  five  drawings  in  serial  order  and  by  comparisons  verify  the 
following  statements: 

(a)  In  the  conus  medullaris  (sacro-coccygeal  region),  the  gray  sub- 
stance is  surrounded  by  a  comparatively  thin  mantle  of  white  sub- 
stance. The  dorsal  horns  are  nearly  as  thick  as  the  ventral  horns 
and  the  gray  commissure  is  relatively  thicker  than  in  any  of  the 
other  regions.  Is  there  a  lateral  horn?  Why  should  the  white 
substance  be  relatively  less  abundant  here,  and  what  axone  systems 
predominate  in  it? 

(b)  In  the  lumbar  region,  the  white  substance  begins  to  predominate 
and  the  number  of  large  cell-bodies  here  is  relatively  large.  Why? 
Is  there  a  lateral  horn?  Compare  the  posterior  funiculi  here 
with  those  of  the  other  sections  and  explain  their  differences. 
Note  the  shape  of  the  section. 

(c)  The  thoracic  region  is  characterized  by  its  relatively  small  arnount 
of  gray  substance.  The  ventral  and  dorsal  horns  together  form 
two  slender  crescents  united  across  the  mid-line  by  a  thin  gray 
commissure  situated  relatively  nearer  the  ventral  side  of  the  section. 
The  nucleus  dorsalis  modifies  the  shape  of  the  cervix  of  the  dorsal 
horn.  Compare  the  shape  and  size  of  its  cells  with  those  of  the 
ventral  horn.  What  fasciculus  arises  from  it?  Which  of  the  cell 
groups  mentioned  above  are  represented  in  the  ventral  horn  and 
what  muscles  are  supplied  by  their  axones  ?  Especially  to  be  noted 
is  the  increase  of  the  posterior  funiculi.  Is  the  white  substance 
of  the  entire  section  absolutely,  as  well  as  relatively,  greater  than  in 
the  sections  from  the  more  caudal  regions?  Why?  Is  the  reticular 
formation  evident  here? 


THE    ENCEPHALON.  1 25 

(d)  The   cervical   region   shows   a  decided  increase   in   the   absolute 

amount  of  white  substance.     Why?     The  fasciculus  gracilis  can 

be  easily  distinguished  from  the  fasciculus  cuneatus  and  the  lateral 

fasciculi,  in  the  region  of  the  enlargement,  have  so  increased  as  to 

give  the  section  an  oval  shape.     The  ventral  horns  are  much  thicker 

in  the  enlargement  than  in  the  thoracic  region  and  there  is  a  well 

marked  lateral  horn.     Why?     The  section  from  the  first  cervical 

segment  shows  the  gray  substance  reduced  to  a  figure  similar  to 

that  in  the  thoracic  region.     The  amount  of  white  substance  here 

is   also    somewhat   decreased.     Why   should   it   decrease   at   all? 

Explain  the  production  and  significance  of  this  enlargement  of  the 

spinal  cord.     Why  do  both  the  ascending  and  descending  fasciculi 

show  increase  in  passing  from  the  conus  medullaris  towards  the 

encephalon?     Do  all  the  fibres  of  the  dorsal  roots  of   the  spinal 

nerves  reach  the  brain?     Explain  the  variations  in  the  amount 

of  the  fasciculi  proprii  at  the  different  levels. 

6.  Under  higher  magnification,  draw  the  gray  commissure  of  the  section 

from  the  lumbar  region,  showing  in  detail  the  central  canal,  the  central 

gelatinous  substance  and  the  ventral  white  commissure.     What  is  the 

origin  and  distribution  of  the  fibres  composing  the  latter?     Is  there  a 

dorsal  white  commissure?     Are  the   ependyfna  cells   ciliated?     Is  the 

lumen  of  the  central  canal  maintained  throughout  the  spinal  cord? 

II.  THE  ENCEPHALON  (brain). 

Human  brains  removed  and  preserved  in  formalin  by  the  embalmer,  and 
fresh  sheep  heads,  obtained  from  the  butcher,  will  be  supplied. 

A.  In  situ.     Fresh.   Sheep's  Brain.   Introductory  Exercise. 
I.  Removal. 

(a)  Grasp  the  sheep  head  firmly  in  a  vise,  cranium  upward,  and  with 
a  saw  make  a  transverse  cut  involving  the  anterior  rims  of  the 
two  orbits.  Then,  along  each  side  of  the  head,  beginning  each  cut 
by  sawing  obliquely  through  the  occipital  condyle  into  the  lateral 
portion  of  the  foramen  magnum  and  thence,  let  the  line  of  the  saw, 
slanting  slightly  inward,  pass  close  to  the  orbit  and  join  the  trans- 
verse cut.  Work  lightly  and  do  not  let  the  saw  cut  into  the  cranial 
cavity.  With  chisel  or  skull-wrench  break  the  vault  of  the  cranium 
loose  and  carefully  lift  it  from  behind  and  remove  it,  freeing  the 
adherent  dura  mater  from  the  bone  with  a  scalpel  handle  and 
taking  care  not  to  injure  the  cranial  contents.  With  blunt-pointed 
scissors,  cut  the  dura  mater  along  each  side  just  below, the  line  of 
the  saw. 

(b)  With  scalpel  handle,  free  each  olfactory  bulb  from  the  lamina 
cribosa  of  the  ethmoid  bone,  noting  the  filaments  of  the  olfactory 


126  LABORATORY    GUIDE    FOR    HISTOLOGY. 

nerve  passing  through  the  foramina  of  the  lamina  and  entering 
the  ventral  aspect  of  the  bulb.  Then,  beginning  from  behind, 
lea^dng  the  dura  mater  adherent  to  the  floor  of  the  cranium,  lift 
the  medulla  oblongata  and,  as  the  cerebral  nerves  come  into  view, 
sever  each  pair  as  close  to  their  respective  foramina  as  possible. 
The  hypophysis  is  situated  in  a  pocket  of  the  dura  mater  (dia- 
phragma  sellae)  in  the  hypophyseal  fossa  of  the  cranium  and  may 
be  cut  out  with  the  scalpel  without  breaking  the  infundibulum  by 
which  it  is  attached  to  the  brain.  The  optic  nerves  must  be  severed 
near  the  optic  chiasma,  at  their  exit  from  their  foramina.  Lay  the 
specimen  in  a  dissecting  pan,  dorsal  surface  upward. 

2.  The  Meninges. 

(a)  Gently  lift  a  portion  of  the  dura  mater  in  situ  on  the  dorsal  surface 
of  the  encephalon  and  identify  the  sub-dural  cavity,  the  arachnoidea 
of  the  encephalon,  the  subarachnoid  cavity,  the  pia  mater  of  the 
encephalon,  and  the  subarachnoid  trabeculae  connecting  the 
arachnoidea  and  pia.  What  is  the  significance  of  the  latter?  Note 
that  the  dura  mater  consists  of  two  closely  related  layers,  the  outer 
of  which  serves  as  the  internal  periosteum  of  the  cranial  bones. 
The  two  layers  are  separable  in  occasional  localities  and  between 
them  lie  veins,  venous  lacunae  and  venus  sinuses.  Explain  the 
absence  of  two  layers  in  the  spinal  dura  mater,  and  compare  the 
epidural  cavity  of  the  vertebral  canal  and  its  venous  plexus  with  the 
spaces  between  the  two  layers  here  and  the  venous  channels  con- 
tained. Test  and  explain  the  fact  that  the  dura  mater  is  more  firmly 
adherent  to  the  bone  in  the  floor  of  the  cranium  than  to  the  vault. 

(b)  Remove  the  dura  mater  from  the  dorsal  surface  of  the  encephalon, 
and,  comparing  with  a  demonstration  specimen  of  the  human,  note 
the  following  infoldings  or  duplications  of  its  inner  layer: 

(i)  The  falx  cerebri,  extending  into  the  longitudinal  fissure  between 
the  cerebral  hemispheres  and  containing  the  superior  and 
inferior  sagittal  sinuses,  and,  posteriorly,  the  sinus  rectus,  running 
along  the  line  of  its  junction  with, 

(2)  The  tentorium  cerebelli,  extending  into  the  transverse  fissure 
between  the  cerebrum  and  the  cerebellum,  its  superior  border 
containing  the  tentorial  notch  (incissura)  which  saddles  the 
mesencephalon. 

(3)  The  falx  cerebelli,  present  in  the  human  specimen,  extending  in 
the  groove  (cerebellar  notch)  between  the  cerebellar  hemispheres, 
but  absent  in  the  sheep  for  the  reason  that  the  cerebellar  hemis- 
phere are  less  developed. 

(4)  In  the  floor  of  the  cranium,  determine  the  relations  of  the  dia- 
phragma  sellae  to  the  hypophyseal  fossa,  the  hypophysis  and  the 


TOPOGRAPHY  OF  THE  ENCEPHALON.  I 27 

infundibulum,  and  dissect  out  one  of  the  semilunar  (Gasserian) 
ganglia,  determining  the  formation  and  position  of  the  "  Meckel's 
caves." 

(c)  Of  the  arachnoidea  of  the  encephalon,  determine  the  boundaries 
and  contents  of  the  cerebello-medullary  cistern,  the  cistern  of  the 
lateral  fossa  of  the  cerebrum,  and  the  chiasmatic  and  interpedun- 
cular cisterns.  What  are  the  arachnoid  granulations  (Pacchionian 
bodies)  and  their  relations  to  the  cerebrospinal  lymph? 

(d)  Note  that  the  pia  mater  of  the  encephalon  is  closely  applied  to  its 
surface  throughout  and  sends  vascular  duplications  into  its  two 
great  fissures: 

(i)  The  tela  chorioidea  of  the  fourth  ventricle,  lying  in  the  trans- 
verse cerebellar  fissure  and  roofing  over  the  inferior  portion  of  the 
fourth  ventricle,  and 
(2)  The  tela  chorioidea  of  the  third  ventricle  (velum  interpositum), 
extending  into  the  transverse  cerebral  fissure  and  roofing  over 
the  cavity  of  the  third  ventricle. 
Now  remove  the  mandible  with  the  muscles  attached  and  place 
the    remainder   of    the    sheep's    head    into   5   per   cent,   formalin 
(2J  per  cent,  formaldehyde)  that   it  may  be  preserved  for  use  in 
the  study  of  the  organs  of  special  sense. 

3.  General  topography  of  the  encephalon  (sheep). 

(a)  Identify  and  note  the  position  of  the  following: 

(i)  The  frontal,  temporal  and  occipital  poles  of  the  cerebrum;  the 
lateral  cerebral  fissure,  the  temporal  lobe,  and  hippocampal 
gyrus;  the  hypophysis,  the  infundibulum  and  tuber  cinereum; 
the  mammillary  bodies,  peduncles  of  cerebrum  (crura  cerebri) 
and  interpeduncular  fossa;  the  pons  with  basilar  sulcus  and 
brachia  of  pons;  the  cerebellar  hemispheres  with  floccular  lobes 
and  the  superior  and  inferior  vermis ;  the  medulla  oblongata  with 
anterior  (ventral)  median  fissure,  pyramids,  decussation  of  the 
pyramids,  olives,  lateral  and  posterior  (dorsal)  funicuH,  and 
restiform  bodies.  What  is  the  relation  of  the  pons  and  restiform 
bodies  to  the  cerebellum?  Note  fibres  crossing  each  restiform 
body  (external  arcuate  fibres)  giving  it  the  appearance  which  sug- 
gests its  name  and  the  very  evident  trapezoid  body  of  the  sheep. 

(2)  Press  open  the  longitudinal  fissure  of  the  cerebrum  and  note  the 
corpus  callosum.  Of  what  substance  is  it  composed  and  what 
is  its  e\'ident  significance  ? 

(3)  Sever  the  corpus  callosum  along  the  mid-line  and  note  the 
longitudinally  disposed  and  paired  bodies  of  white  substance,  the 
fornix.  Below  the  fornix,  observe  the  paired  masses  of  gray 
substance,  the  thalami,  covered  by  the  non-nervous  tela  chorioidea 


128  LABORATORY    GUIDE    FOR    HISTOLOGY. 

of  the  third  ventricle.  Connecting  the  corpus  callosum  with 
the  fornix,  note  the  vertically  placed  septum  pellucidum. 
(4)  Press  apart  the  occipital  poles  and  the  cerebellum  and  note  the 
quadrigeminate  bodies  (the  mesencephalon)  with  the  epiphysis 
(pineal  body)  resting  upon  the  superior  colliculi.  Distinguish 
the  anterior  medullary  velum  extending  from  the  inferior  colliculi 
and  forming  the  roof  over  the  anterior  portion  of  the  fourth 
ventricle. 

(b)  On  the  basal  surface,  identify  the  12  pairs  of  cranial  nerves,  giving 
the  number  and  name  of  each,  and  its  distinguishing  peculiarities. 
What  can  be  said  especially  of  the  olfactory  nerve  ?  With  what  is 
the  tuber  cinereum  continuous  ?  Note  the  inferior  extension  of  the 
longitudinal  fissure  of  the  cerebrum. 

(c)  Ventricles  of  the  encephalon. 

(i)  Divide  the  cerebellum  along  the  vermis,  taking  care  not  to  injure 
the  structures  below  it,  and  remove  one  of  the  halves,  observing 
and  naming  the  structures  severed  in  the  removal.  Note  the 
chorioid  tela  and  plexus  of  the  fourth  ventricle  and  the  rhomboid 
fossa  constituting  the  floor  of  the  ventricle,  with  its  pointed,  in- 
ferior termination,  the  calamus  scriptoris,  at  which  the  ventricle 
is  continuous  into  the  central  canal  of  the  medulla  oblongata  and 
spinal  cord.  Observe  that  the  superior,  or  anterior,  portion  of  the 
fourth  ventricle  extends  under  the  anterior  medullary  velum  and, 
with  a  probe,  determine  that  this  is  continuous  with  the  third 
ventricle  by  way  of  the  aqueduct  of  the  cerebrum  (aqueduct  of 
Sylvius)  which  passes  under  the  quadrigeminate  bodies. 

(2)  The  third  ventricle,  covered  by  its  chorioid  tela  and  continuous 
into  the  lateral  ventricles  of  the  cerebrum  by  way  of  the  two 
interventricular  foramina  (foramina  of  Monro).  Note  the 
gray,  intermediate  mass  (middle  commissure)  connecting  the 
thalami  across  the  ventricle. 

(3)  Tear  one  of  the  cerebral  hemispheres,  noting  the  shape  of  the 
lateral  ventricle  with  its  chorioid  plexus,  its  anterior  horn,  central 
part,  posterior  horn,  and  inferior  horn.  What  is  the  chorioid 
plexus  and  into  which  of  the  horns  does  it  extend?  Note  the 
caudate  nucleus.  Its  structural  nature,  its  extent,  and  why  its 
name  ? 

(d)  Identify  the  following  general  divisions  of  the  encephalon. 
(i)  Rhombencephalon. 

(i)  Medulla  oblongata. 

,..,    ^,  ,    ,         f  cerebellum, 

(n)  Metencephalon    { 

\  pons. 

(iii)  Isthmus  of  rhombencephalon. 


SUPERFICIAL    BLOOD-VESSELS.         .  I2g 

(2)   Cerebrum. 

(\)    Mesenrenhalnn  /  q^adrigeminate  bodies. 

(I)  IVXcbCIlLcUUcilOn    <  1111 

[  cerebral  peduncles. 

'  ....   _  1    1       f  diencephalon  (thalami,  etc.). 

(II)  Prosencephalon  J      ,  ,    ,       .        ,      ,  1       .     , 

[  telencephalon  (cerebral  hemispheres,  etc.). 

B.  The  Human  Encephalon  (detailed  study). 

About  twelve  hours  after  the  process  of  embalming  and  injection  of  the 
blood-vessels  of  the  subjects  for  the  dissecting  room,  the  brains  are  removed 
and  preserved  separately  in  10  per  cent,  formalin.  They  should  be  washed  in 
water  for  at  least  one  hour  before  beginning  work  on  them,  should  be  kept 
moist  while  working  and,  between  each  period  of  work,  should  be  kept  in  a 
2  per  cent,  solution  of  formalin. 

I.  External  features. 

(a)  Identify  all  the  structures  mentioned  in  A,  3,  (a),  (i)  and  (2)  above. 
Explain  the  difference  in  the  direction  of  the  human  medulla 
oblongata  from  that  of  the  sheep.  As  compared  with  the  sheep's 
brain,  note  the  more  distinct  pyramids  and  olives,  the  relatively 
larger  cerebellum  and  pons,  the  more  distinctly  separated  mammil- 
lary  bodies,  the  relatively  much  larger  cerebrum  with  much  more 
developed  frontal  and  temporal  regions  and  more  marked  lateral 
cerebral  fissures;  the  much  less  developed  olfactory  bulbs  and  tracts 
but  the  more  distinct  olfactory  trigone.  Carefully  examine  the 
remains  of  the  arachnoidea  and  note  variations  of  the  pia  mater  upon 
the  dorsal  and  ventral  aspects  of  the  brain.  How  does  the  pia  in 
the  sulci  differ  from  that  on  the  summits  of  the  gyri  ? 

(b)  Superficial  blood-vessels. 

Note  that  the  arteries  of  the  brain  approach  and  the  veins  leave  it 
from  its  ventral  aspect.  Its  arterial  supply  is  derived  from  the 
two  vertebral  and  the  two  internal  carotid  arteries.  Of  the  larger 
vessels  trace  the  following: 
.  The  two  vertebral  arteries  unite  near  the  inferior  border  of  the 
pons  to  form  the  single  basilar  artery.  This  passes  along  the  pons 
in  its  basilar  sulcus  and  gives  off  the  inferior  and  superior  cere- 
bellar arteries  and  the  smaller  rami  to  the  pons.  At  the  superior 
border  of  the  pons,  the  basilar  artery  bifurcates  into  the  two  posterior 
cerebral  ateries,  which  branch  repeatedly  to  spread  over  the  occip- 
ital regions  of  the  cerebral  hemispheres.  Near  their  origin,  the 
posterior  cerebral  arteries  give  off"  the  posterior  communicating 
arteries,  one  for  each  side,  which  pass  forward,  encircling  the 
mammillary  bodies  and  the  tuber  cinereum,  and  then  join  the  in- 
ternal carotid  arteries  at  the  outer  sides  of  the  optic  chiasma. 


130  LABORATORY    GUIDE    FOR    HISTOLOGY. 

Each  internal  carotid  artery  divides  into  three  branches: 
(i)  The  chorioid  artery,  the  smallest,  passes  dorsally,  around  the 
peduncles  of  the  cerebrum  and  inward  to  the  chorioid  plexuses 
of  the  ventricles. 

(2)  The  middle  cerebral  artery,  the  largest,  breaks  up  into  its  larger 
branches  in  the  lateral  cerebral  fissure  and  spreads  over  the 
lateral  surface  of  the  brain. 

(3)  The  anterior  cerebral  artery  passes  forward  into  the  ventral  part 
of  the  great  longitudinal  fissure  and  becomes  the  chief  supply 
of  the  frontal  and  medial  portions  of  the  cerebral  hemisphere. 
The  two  anterior  cerebral  arteries  are  connected  across  the 
mid-line  just  in  front  of  the  chiasma,  by  the  single,  short  anterior 
communicating  artery.  Thus  a  circle  ("the  circle  of  Willis") 
is  formed,  enclosing  the  chiasma,  the  tuber  cinereum  and  the 
mammillary  bodies.  Enumerate  the  branches  which  contribute 
to  the  circle.  Work  out  the  names  and  distribution  of  the 
principal  branches  of  the  arteries  named. 

The  external  veins  of  the  encephalon  lie,  for  the  most  part, 
superficial  to  the  arteries  and  course  in  the  arachnoidea  and  dura 
mater  and,  therefore,  their  study  must  be  made  chiefly  from  the 
foramina  and  remaining  meninges  within  the  cranium  of  the 
subject  in  the  dissecting  room.  The  veins  arise  within  the  sub- 
stance of  the  brain  and  the  chorioid  plexuses,  converge  into  larger 
branches  in  the  pia  mater  and  subarachnoid  space,  pass  through 
the  arachnoid  and  empty  into  the  venous  sinuses  and  lacunas 
situated  between  the  two  layers  of  the  dura  mater.  The  large 
transverse  sinus  is  situated  in  the  tentorium  cerebelli.  It  is 
joined  in  the  mid-line  by  the  superior  sagittal  sinus  which  runs 
the  entire  superior  length  of  the  falx  cerebri  and  falx  cerebelli 
and  is  fed  by  the  various  superior  cerebral  and  superior  cere- 
bellar veins.  The  inferior  sagittal  sinus  runs  in  the  inferior 
border  of  the  falx  cerebri  and,  in  the  tentorium  cerebelli,  is  con- 
tinuous into  the  straight  sinus,  which  opens  into  the  transverse 
sinus  near  the  juncture  of  this  with  the  superior  sagittal  sinus. 
In  each  of  the  lateral  ventricles,  the  chorioid  vein,  assembled  along 
the  chorioid  plexus,  and  the  terminal  vein,  assembled  along  the 
border  of  the  caudate  nucleus,  unite  with  each  other  at  the  in- 
terventricular foramen  to  form  one  of  the  internal  cerebral  veins. 
The  two  internal  cerebral  veins  (veins  of  Galen)  pass  backward 
in  the  tela  choroidea  of  the  third  ventricle,  receiving  the  basal 
veins  and  smaller  twigs,  and  unite  in  the  mid-line  to  form  the 
vena  magna  of  the  cerebrum,  which  latter  joins  the  straight 
sinus  at  its  junction  with  the  inferior  sagittal  sinus. 
The  lateral  limbs  of  the  transverse  sinus  (lateral  sinuses)  empty 


THE  CRANIAL  NERVES.  I3I 

into  the  internal  jugular  veins  and  thus  the  blood  passes  out  of 
the  cranium  at  either  side.  In  the  dura  mater  of  the  floor  of  the 
cranium,  the  two  cavernous  sinuses  empty  into  the  internal  jug- 
ular veins  by  way  of  the  two  inferior  petrosal  sinuses. 

(c)  The  Cranial  Nerves. — Give  special  attention  to  the  relative  size, 
form,  locality  of  attachment,  origin  and  function  of  the  fibers  of 
each  of  the  twelve  pairs: 
(i)  The  Olfactory    arises    in    the    olfactory    region    of    the    nasal 
epithelium  and  terminates  in  the  olfactory  bulb.     Sensory. 

(2)  The  Optic  passes  obliquely  medianward  from  the  ocular  bulb 
to  the  optic  chiasma;  thence,  as  optic  tract,  its  fibers  pass  around 
the  cerebral  peduncle  to  the  thalamus  (pulvinar),  the  lateral 
geniculate  body  and  the  superior  colliculi.  Sensory.  Why  may 
it  be  considered  an  intercerebral  tract  instead  of  a  typical  nerve  ? 

(3)  The  Oculomotor  emerges  in  its  sulcus  in  the  medial  border  of  the 
cerebral  peduncle  and  through  the  posterior  perforated  substance 
of  the  interpeduncular  fossa.     Motor. 

(4)  The  Trochlear,  smallest  of  the  cranial  nerves,  arises  from  the 
dorsal  aspect  of  the  isthmus  of  the  rhombencephalon  near  the 
inferior  border  of  the  inferior  colliculi  (frenulum  of  anterior 
medullary  velum),  passes  downward  around  the  cerebral  peduncle 
and  comes  into  view  on  the  ventral  aspect  of  the  brain  near  the 
superior  margin  of  the  pons.     Motor. 

(5)  The  Trigeminus,  largest  of  the  cranial  nerves,  consists  of  two 
roots:  The  sensory  root  or  major  portion  of  the  nerve  enters 
the  rhombencephalon,  piercing  the  superior  and  lateral  aspect 
of  the  pons.  The  small,  cylindrical,  motor  root  or  minor  portion 
emerges  through  the  lateral  aspect  of  the  pons  close  to  the  supero- 
dorsal  margin  of  the  sensory  root.  In  emerging,  its  fibers  mingle 
with  those  of  the  sensory  root,  but  soon  assemble  into  the  distinct 
bundle  which  then  loops  around  the  medial  margin  of  this  root. 
Shape  and  location  of  the  ganglion  of  origin  of  the  major  portion  ? 
Name  and  direction  of  the  three  nerves  which  arise  from  it? 
Which  of  them  is  joined  by  the  motor  root? 

(6)  The  A  bdiicens  leaves  the  medulla  oblongata  at  the  inferior  margin 
of  the  pons  in  the  transverse  fossa  between  this  margin  and  the 
base  of  the  pyramid  and  near  the  ventral  median  fissure  (foramen 
cecum),  and  runs  forward  and  lateralward  over  the  surface  of  the 
pons.     Motor. 

(7)  The  Facial,  larger  nerve  than  the  abducens,  appears  in  the 
transverse  fossa  at  the  inferior  margin  of  the  pons,  lateral  to  the 
emergence  of  the  abducens.  It  consists  of  two  roots,  a  large 
motor  root  and  a  small  sensory  root,  or  pars  intermedia  (interme- 


132  LABORATORY    GUIDE    FOR   HISTOLOGY.  . 

diate  nerve),  which  latter  comprises  its  more  lateral  portion.  The 
fibers  of  the  two  roots  usually  blend  so  that  the  double  character 
of  the  nerve  is  more  or  less  concealed  in  its  intracranial  portion 
and,  when  separated  beyond,  the  smaller  root  carries  some 
motor  fibers.  Mixed.  What  and  where  situated  is  the  ganglion 
of  origin  of  the  sensory  fibers? 

(8)  The  Acoustic  (Auditory). — Large  nerve  which  enters  the  rhom- 
bencephalon lateral  from  but  near  the  facial  and  at  the  inferior 
margin  of  the  brachium  of  the  pons,  superior  and  dorsal  to  the 
olive.  It  consists  of  two  roots  or  divisions:  The  vestibular  root 
(vestibular  nerve),  the  more  medial  of  the  two  roots,  enters  on  the 
ventral  side  of  the  restiform  body  and  dorsal  to  the  line  of  the 
olive.  The  more  lateral,  cochlear  root  (cochlear  nerve),  in 
enering,  arches  around  the  dorsal  and  outer  surface  of  the  resti- 
form body  and  some  of  its  fibers  course  in  the  floor  of  the  fourth 
ventricle.  Sensory.  Where  are  the  ganglia  of  origin  of  the 
separate  roots?  Why  could  the  two  roots  be  considered  as 
separate  cranial  nerves  ? 

(9)  The  Glossopharyngeal. — Attached  to  the  medulla  oblongata 
in  five  to  seven  root-filaments  in  the  superior  part  of  the  sulcus 
between  the  olive  and  restiform  body  and  in  line,  longitudinally, 
with  the  facial  nerve.  Mixed  nerve,  though  when  traced  out- 
w^ard,  all  the  filaments  blend  into  a  single  trunk  in  which  are 
situated  two  ganglia  of  origin  of  its  sensory  fibers.  Names  and 
locations  of  the  ganglia? 

(10)  The  Vagy,s  (Pneumo gastric). — Attached  to  medulla  in  ten  to 
fifteen  root  filaments,  in  the  same  sulcus,  inferior  to  and  in  line 
with  those  of  the  Glossopharyngeal.  Filaments,  when  followed, 
converge  into  a  single  stout,  cylindrical  trunk.  Like  the  ninth, 
it  is  a  mixed  nerve  whose  sensory  axons  arise  in  two  ganglia  inter- 
posed in  its  trunk.     Names  and  situation  of  the  ganglia? 

(11)  The  (Spinal)  Accessory. — Emerges  from  the  lateral  aspect  of 
the  medulla  oblongata  and  the  upper  four  to  six  segments  of  the 
spinal  cord  in  a  series  of  rootlets  which  contribute  to  form  a  trunk 
which  runs  upward  and  parallel  to  the  lateral  surface  of  the  medulla. 
Consists  of  an  accessory  or  superior  part,  consisting  of  the  three  to 
six  rootlets  arising  from  the  medulla  in  line  with  and  below  the 
filaments  of  the  vagus,  and  a  spinal  or  inferior  part,  the  remain- 
ing rootlets  which  emerge  from  the  lateral  funiculus  of  the 
spinal  cord,  dorsal  to  the  denticulate  ligament  and  between 
the  lines  of  attachment  of  the  dorsal  and  ventral  roots  of  the 
spinal  nerves.     Motor.     Distribution  and  relation  to  the  vagus  ? 

(12)    The  Hypoglossus. — Emerges  from  the  medulla  oblongata  in  ten 
to  sixteen  root  filaments,  between  the  pyramid  and  the  olive, 


THE    CEREBRUM.  1 33 

in  the  upper  end  of  the  ventro-lateral  sulcus,  and  in  line  with  the 
ventral  root  filaments  of  the  spinal  nerves.  Root  filaments 
usually  first  converge  to  form  two  bundles  which  later  unite  into 
the  single  trunk  of  the  nen-e.     Motor. 

Note  that,  exclusive  of  the  olfactor}-  and  optic,  the  cranial 
nerves  are  attached  to  the  encephalon  along  two  dififerent  lines: 
a  ventro-lateral  line  and  a  lateral  line.  Make  a  tabulation  of  the 
twelve  pairs,  comparing  their  functions,  the  character  of  their 
attachment,  their  size  and  the  lines  of  their  attachment, 
(d)  General  study  of  the  base  of  the  encephalon. 

Remove  the  blood-vessels  of  the  base  of  the  encephalon  and  care- 
fully peel  ofi"  the  pia  mater  from  the  structures  near  the  mid-line, 
taking  care  not  to  injure  the  nerve-roots  and  the  tuber  cinereum. 
WTience  do  the  nerves  obtain  their  sheaths  ?  Look  up  the  peculiar 
nature  of  the  sheath  of  the  optic  nerve.  Observe  that  the  olfactory 
tract  runs  backward  from  the  olfactory  bulb  in  the  olfactory  sulcus, 
between  the  orbital  gyri  and  the  gyrus  rectus,  and  terminates  in  the 
olfactory  trigone,  the  three  striae  of  which  disappear  in  the  anterior 
perforated  substance.  A\Tiat  is  the  apparent  nature  of  the  anterior 
and  posterior  perforated  substances  and  what  are  the  perforations  ? 
What  is  the  apparent  course  of  the  fibers  of  the  cerebral  peduncles 
and  what  is  their  function?  Study  the  course  of  the  fibers  of  the 
pons  as  they  pass  into  the  brachium  pontis  of  either  side.  What 
factors  produce  the  basilar  sulcus?  Course  of  the  oblique  fibers 
of  the  pons?  How  do  the  gyri  of  the  cerebral  hemispheres  differ 
from  those  of  the  cerebellum?  Shape  and  gyri  of  the  flocculus? 
Make  a  line  drawing  of  the  entire  base  of  the  encephalon,  exclusive 
of  the  blood-supply,  showing  and  naming  the  important  features. 

2.  The  divisions  of  the  encephalon. 
(a)  The  Cerebrum. 

(i)   Tlie  Prosencephalon. 

(i)  Medial  Surface. — With  sharp  scalpel  cut  one  of  the  cerebral 
peduncles  transversely  just  posterior  to  the  mammillary  body, 
taking  care  not  to  injure  the  mesencephalon.  Then  turn  the 
specimen  convex  surface  upward,  press  open  the  longitudinal 
fissure  and,  with  brain  knife,  carefully  di\'ide  the  corpus 
callosum  along  the  mid-line.  Continue  the  incision  so  that 
the  knife  divides  the  fornix,  severs  the  intermediate  mass, 
passes  between  the  mammillary  bodies,  splits  the  tuber  ciner- 
eum, and  passes  through  the  middle  of  the  optic  chiasma. 
Carefully  remove  sufficient  of  the  pia  mater  from  the  hemisphere 
thus  detached,  then  lean   it  slightlv  lateralward  on  its  ventral 


134  LABORATORY    GUIDE    FOR    HISTOLOGY. 

surface  and  make  a  drawing  of  the  entire  medial  surface  and 
medial  portion  of  the  ventral  surface  of  prosencephalon,  show- 
ing the  shape  and  position  of  all  the  structures  in  view  and 
attach  their  names.  Indicate  the  four  parts  of  the  corpus 
callosum  and  give  careful  attention  to  the  names,  position  and 
extent  of  the  various  sulci  to  be  seen.  Are  the  sulci  of  the 
two  hemispheres  alike  ?  What  are  the  relations  of  the  septum 
pellucidum,  lamina  rostralis  and  lamina  terminalis  to  the  corpus 
callosum.  Relation  of  the  fornix  to  the  mammillary  body? 
Relation  of  the  columns  of-the  fornix  to  the  interventricular 
foramina?  What  is  the  tenia  of  the  fornix ?  Structure  of  the 
chorioid  tela  of  the  third  ventricle?  Shape  of  the  third  ven- 
tricle and  realtion  of  the  infundibulum  and  tuber  cinereum  to 
its  cavity?  Compare  the  function  of  the  anterior  commissure 
with  that  of  the  corpus  callosum.  Slit  the  septum  pellucidum 
and  note  the  caudate  nucleus  in  the  lateral  ventricle.  Ascer- 
tain the  shape  and  disposition  of  this  nucleus  from  text  illus- 
trations. Note  the  shape  of  the  thalamus.  What  is  the 
pulvinar  thalami? 
(ii)  Identify  the  two  divisions  of  the  prosencephalon,  determining 
the  position  and  relationship  of  the  parts  composing  them  as 
follows: 

The  diencephalon,  comprising  the  thalamencephalon  (thala- 
mus, metathalamus  and  epithalamus)  and  the  mammillary 
portion  of  the  hypothalamus,  and. 

The  telencephalon,  comprising  the  optic  portion  of  the 
hypothalamus,  the  optic  nerves  (and  retina),  and  the  cerebral 
hemispheres  (striate  bodies,  olfactory  bulbs  and  tracts,  and  the 
cerebral  cortex). 

To  which  of  these  divisions  do  the  epiphysis  (pineal  body)  and 
the  hypophysis  (pituitary  body)  belong?  Identify  and 
ascertain  the  significance  of  the  habenulai,  commissure  of 
habenulse,  pineal  recess,  medullary  striae  and  tenia  of  thalamus. 
What  function  of  the  pulvinar  and  the  geniculate  bodies  is 
apparent  ? 
(iii)  The  Lobes  of  the  Cerebrum  (telencephalon). — First,  for  the 
purposes  of  orientation,  fix  in  mind  the  name  and  extent  of  the 
different  borders  of  the  hemispheres,  and  as  land  marks,  care- 
fully identify  the  central  sulcus  (fissure  of  Rolando),  the  parieto- 
occipital fissure,  the  lateral  (Sylvian)  fissure,  the  hippocampal 
fissure,  and  the  parts  of  the  sulcus  singuli,  and  then  determine 
the  extent  and  component  parts  of  the  lobes  as  follows: 
;  (la)   The   Frontal  Lobe. — Convex   surface:    the    anterior  central 

gyrus,   the   superior  and   middle  frontal   gyri,   the  inferior 


LOBES    OF    THE    CEREBRUM.  135 

frontal  gyri  with  opercular,  triangular  and  orbital  parts, 
and  the  sulci  separating  these  gyri.  Medial  surface:  superior 
frontal  gyrus,  paracentral  lobule  and  rostral  sulcus.  Ventral 
surface:  gyrus  rectus,  olfactory  sulcus,  and  gyri  and  sulci 
orbitales. 
(2a)  The  Parietal  Lobe. — Convex  surface:  posterior  central  gyrus, 
superior  and  inferior  parietal  lobules,  the  latter  containing 
the  supramarginal  and  angular  gyri,  and  the  sulci  separating 
these  parts.  Medial  surface:  the  precuneus  and  a  portion 
of  the  paracentral  lobule. 

(3a)  The  Occipital  Lobe. — Convex  surface:  superior  and  lateral 
occipital  gyri  and  sulci.  Medial  surface:  the  cuneus,  the 
calcarine  fissure  and  the  posterior  extremity  of  the  lingual 
gyrus.  Tentorial  surface:  posterior  portions  of  the  lingual 
and  fusiform  gyri  with  that  part  of  the  collateral  fissure 
which  lies  between  them. 

(4a)  The  Temporal  Lobe. — Separated  from  the  frontal  and  parietal 
lobes  by  the  lateral  fissure  of  the  cerebrum  and  comprising 
the  superior,  middle  and  inferior  temporal  gyri  and  sulci, 
and  the  anterior  portions  of  the  fusiform  and  lingual  gyri 
with  the  collateral  fissure  between  them. 

(5a)  The  Island  (central  lobe). — Expose  by  pressing  apart 
the  lips  of  the  lateral  fissure  (operculum)  and  note  the 
circular  sulcus,  short  gyri,  long  gyrus  and  threshold 
of  the  island.  Explain  the  processes  of  development 
which  have  resulted  in  the  position  and  configuration  of 
this  lobe. 

(6a)  The  Rhinencephalon  (olfactory  lobe  and  limbic  lobe). — -Olfac- 
tory bulb,  tract  and  trigone  (name  the  striae);  parolfactory 
area,  subcallosal  gyrus,  anterior  perforated  substance, 
gyrus  fornicatus;  the  fornix,  the  mammillary  body  and  a 
part  of  the  septum  pellucidum.  Name  and  identify  the 
parts  of  the  complicated  gyrus  fornicatus.  Give  the  reasons 
for  the  names  given  the  different  parts  of  the  hippocampus. 
Look  up  the  origin  and  course  of  the  thalamomammillary 
fasciculus  and  the  destination  of  each  of  the  olfactory  strice. 

Explain  the  formation  of  the  gyri  and  sulci  of  the  encephalon  in  general. 
Which  are  the  first  to  appear?  Name  the  parts  of  the  operculum  and  the 
gyri  which  contribute  to  each  part.  What  is  the  somesthetic  area  and  the 
gyri  forming  it?  Give  the  component  parts  of  the  cortical  areas  with  which 
each  of  the  organs  of  special  sense  is  chiefly  concerned.  Extent  and 
components  of  the  so-called  association  centers? 


136  LABORATORY    GUIDE    FOR    HISTOLOGY. 

(2)   The  Mesencephalon. 

From  which  of  the  primary  cerebral  vesicles  is  this  second  division 
of  the  cerebrum  derived  ?  Determine  the  position  and  appearance 
of  the  following  structures  comprising  it.  Dorsal  surface:  the 
superior  and  inferior  colliculi  of  the  corpora  quadrigemina,  the 
brachia  of  each  and  the  furrows  separating  them.  Ventral 
surface:  peduncles  of  cerebrum,  anterior  and  posterior  recesses, 
and  the  posterior  perforated  substance.  The  aqueduct  of  the 
cerebrum  passes  through  the  mesencephalon. 

(b)  The  Rhombencephalon. 

(i)  The  Cerebellum  and  Pons  (Metencephalon). 

(i)  Dorsal  and  lateral  surface  of  the  cerebellum:  Note  that  the 
cerebellar  hemispheres  join  each  other  in  a  medial  ridge,  the 
superior  vermis,  which  disappears  from  view  in  the  marked 
posterior  cerebellar  notch.  Of  the  hemispheres,  identify 
and  name  the  four  lobes  apparent  on  the  dorsal  and  lateral 
surfaces  and  the  fissures  separating  them.  Of  the  superior 
vermis,  identify  the  central  lobule,  the  monticulus,  and  the 
folium.  How  do  the  gyri  and  the  sulci  and  the  distribution 
of  the  superficial  blood-vessels  of  the  cerebellum  differ  from 
those  of  the  telencephalon? 
(ii)  Ventral  surface  of  cerebellum:  Carefully  sever  the  brachium 
of  the  pons  (middle  cerebellar  peduncle)  of  the  same  side  as 
that  from  which  the  cerebral  hemisphere  has  been  removed, 
then  pass  the  brain  knife  vertically  through  the  mid-Hne  along 
the  summit  of  the  monticulus,  taking  care  not  to  injure  the 
floor  of  the  fourth  ventricle,  and  remove  the  half  of  the  cere- 
bellum by  severing  the  anterior  medullary  velum  close  under 
the  central  lobule  of  the  vermis.  On  the  ventral  surface  of  the 
half  removed,  identify,  in  addition  to  the  lobes  already  named, 
the  biventral  and  gracile  lobules,  the  tonsila,  the  flocculus,  and 
the  inferior  vermis  (divided),  the  latter  being  separated  from 
the  hemispheres  on  either  side  by  the  vallecula  and  divided  by 
transverse  fissures  into  the  tuber,  pyramid,  uvula,  and  nodula 
of  the  vermis.  Are  there  secondary  flocculi?  Identify  the 
peduncle  of  the  flocculus  and  the  posterior  medullary  velum. 
Where  and  what  is  the  ligula? 

In  the  cut  surfaces  identify  arbor  vitae,  medullary  body 
medullary  lamina,  cortical  substance,  and,  in  addition  to  the 
middle  peduncle,  determine  the  position  of  the  brachium  con- 
junctivum  (superior  peduncle)  and  the  restiform  body  (inferior 
peduncle).  Function  of  each  of  the  three  peduncles?  What 
is  the  orientation  of  the  cells  of  Purkinje  with  reference  to  the 


THE    MEDULLA    OBLONGATA.  1 37 

cortical  substance  and  to  the  course  and  contour  of  the  gyri 
of  the  cerebeUum? 

Make  a  careful  drawing  oj  the  convex  lateral  surface  of  the 
entire  encephalon  from  the  side  remaining  intact  and  attach 
the  names  to  all  the  parts  in  view. 

(2)  The  Medulla  Oblongata. 

(i)  Dorsal  and  lateral  surfaces:  Note  that  the  posterior  sulcus 
of  the  spinal  cord  becomes  deepened  into  the  posterior  median 
fissure  of  the  medulla  oblongata,  which  latter  is  continuous 
into  the  calamus  scriptorius,  and  that  the  line  of  attachment 
of  the  chorioid  tela  of  the  fourth  ventricle  is  indicated  by  a  torn 
ridge  of  slightly  thickened  pia  mater,  the  taenia  of  the  fourth 
ventricle,  which  crosses  the  mid-line  at  the  junction  of  the 
posterior  fissure  with  the  calamus  scriptorius,  producing  a 
more  or  less  distinct  bridge  over  the  tip  of  the  calamus  scrip- 
torius, known  as  the  obex.  Identify  the  postero-intermediate 
and  the  postero-lateral  sulci;  the  funiculus  gracilis  and  funic- 
ulus cuneatus  (why  funiculus  here?)  terminating  in  slightly 
bulbous  eminences,  viz.,  the  nucleus  of  the  funiculus  gracilis 
(clava)  and  the  tuberculum  cuneatum.  Trace  the  lateral 
funiculus  of  the  spinal  cord  into  the  restiform  body  and  note 
that  the  latter  in  passing  toward  the  brachium  of  the  pons  so 
increases  in  size  as  to  become  the  chief  cause  of  the  decided 
upward  increase  in  the  width  of  the  medulla  oblongata. 
Identify  the  course  of  the  fibres  of  the  acoustic  nerve  passing 
around  the  restiform  body  to  form  the  acoustic  medullary 
striae  in  the  floor  of  the  fourth  ventricle, 
(ii)  Again  identify  the  more  prominent  structures  composing  the 
ventral  surface  of  the  medulla  oblongata,  already  considered 
in  the  study  of  the  ventral  surface  of  the  encephalon  as  a  whole. 
On  both  the  dorsal  and  ventral  surfaces  determine  the  position 
of  the  boundary  lines  separating  the  medulla  oblongata  from 
the  metencephalon  above  and  the  spinal  cord  below. 

(3)  The  floor  oj  the  fourth  ventricle  (rhomboid  fossa). 

Remove  the  half  of  the  anterior  medullary  velum  and  with  it  a 
portion  of  the  brachium  conjunctivum  of  the  side  from  which 
the  hemispheres  have  been  removed,  and  press  the  attached  half 
of  the  cerebellum  slightly  outward  so  as  to  expose  the  entire 
floor  of  the  fourth  venricle.  What  is  its  shape  and  where  and 
with  what  canal  is  it  continuous  ?  Determine  the  position  extent 
and  functional  significance  of  the  following: 
The  medial  eminence,  bounded  by  the  median  sulcus  and  the 
sulcus  limitans,  and  consisting  of  the  eminence  of  the  nucleus 


138  LABORATORY    GUIDE    FOR    HISTOLOGY. 

of  the  vagus  (ala  cinerea),  the  eminence  (trigone)  of  the  hypo- 
glossus,  the  eminence  of  the  facial  and  abducens  (colliculus 
facialis),  the  region  of  the  nucleus  incertus,  and  the  locus  ceru- 
leus;  the  acoustic  tubercle  and  area  with  the  acoustic  medullary 
striae;  the  area  postrema  and  the  funiculus  separans.  Where 
are  the  superior  and  inferior  f oveae  and  what  do  they  separate  ? 
Where  is  the  region  of  the  motor  nucleus  of  the  trigeminus  ?  Of 
the  lateral  recess  of  the  fourth  ventricle  ?  Note  that  the  inferior, 
intermediate  and  superior  portions  of  the  floor  of  the  ventricle 
belong  each  to  a  different  division  of  the  rhombencephalon. 
What  are  these  divisions? 

Make  a  careful  drawing  of  the  floor  of  the  fourth  ventricle, 
including  the  dorsal  aspect  of  the  medulla  oblongata  and  the 
mesencephalon,  and  the  cut  surfaces  of  the  rhombencephalon, 
naming  all  the  prominent  structures. 

3.  Sections  of  the  encephalon. 

General  Directions. — In  making  the  sections  called  for  below,  first  care- 
fully ascertain  the  place  of  each  by  determining  two  or  more  superficially 
indicated  structures  through  which  the  knife  is  to  pass  and  then,  to  avoid 
unevennesses  of  surface,  make  each  section  with  one  stroke  of  the  knife.  Use 
figures  23  and  24  as  guides  in  determining  the  levels  at  which  the  sections 
are  to  be  made.  The  larger  sections  require  a  knife  with  a  thin  and  excep- 
tionally long  blade.  *  The  sections  of  the  regions  of  the  medulla  oblongata, 
pons,  mesencephalpn  and  thalamencephalon  will  be  supplemented  by  sections 
taken  from  corresponding  levels  of  another  specimen  and  stained  by  the 
Weigert  method.  In  these  cases  study  with  a  dissecting  lens  one  of  the  cut 
surfaces  exposed  by  the  passage  of  the  knife  as  directed,  noting  the  position, 
appearances  and  interrelations  of  the  structures  mentioned  under  the  respec- 
tive sections,  compare  with  the  stained  section  and  then,  using  the  stained 
section  under  the  dissecting  microscope,  make  a  careful  drawing.  Use  the 
compound  microscope  for  the  more  detailed  structure  of  the  stained  section. 
In  the  larger  sections  through  the  cerebellar  and  cerebral  hemispheres,  the  more 
important  structures  may  be  distinguished  without  the  aid  of  stained  prepara- 
tions. With  the  cerebral  hemisphere  especially,  the  effect  of  a  symmetrical 
section  through  the  entire  cerebrum  may  be  obtained  by  turning  the  detached 
part  so  that  the  two  cut  surfaces  exposed  by  a  given  passage  of  the  knife  are  in 
plane  with  each  other,  the  medial  aspects  facing  together.  Work  with  the 
specimen  wet  with  water  and,  at  the  end  of  the  period  of  study,  return  all  the 
parts  to  the  jar  of  dilute  formalin.  On  each  drawing,  attach  the  names  of 
all  the  structures  identified,  using  dotted  leaders  radiating  to  the  periphery 
of  the  drawings,  where  the  names  should  be  written  parallel  with  each  other. 
Number  the  drawings  in  series.  Let  the  lowest  section  of  the  medulla  oblongata 
be  "Number  6"  in  order  to  include  in  the  series  the  five  sections  of  the  spinal 


SECTIONS    OF    THE    RHOMBEXCEPHALON.  1 39 

cord  already  studied.  Beginning  with  section  nine,  it  will  suffice  to  draw 
one  half  of  each  section  with  only  a  small  strip  of  the  opposite  side  of  the  mid- 
line included. 

(a)  Sections  of  the  rliomhenceplialon. 

Section  6. — To  pass  transversely  through  the  decussation  of  the 
pyramids.  Draw,  showing  the  position,  form  and  relation  of  the 
following: 

Posterior  median  fissure  (posterior  septum  of  the  spinal  cord)  and 
anterior  median  fissure;  pyramids  and  decussation  of  pyramids; 
anterior  columns,  reticular  formations,  gelatinous  substance  of 
Ralando,  central  canal  and  central  gray  substance;  funiculus  gracilis 
with  portion  of  its  nucleus,  funiculus  cuneatus,  internal  arcuate 
fibers  and  the  lemniscus  (fillet);  spinal  tract  of  the  trigeminus, 
lateral  funiculus  and  root  filaments  of  the  spinal  accessory  nerve. 
Carefully  compare  this  drawing  with  those  of  the  cervical  region 
of  the  spinal  cord  noting  all  modifications  resulting  in  the  transition 
of  the  spinal  cord  into  medulla  oblongata.  How  has  the  position 
of  the  central  canal  changed  ?  Explain  the  changes  in  the  anterior 
and  posterior  columns  (ventral  and  dorsal  horns).  Whence  arise 
the  axones  taking  part  in  the  decussation  of  the  pyramids  and  what 
is  their  relation  to  the  lateral  funiculi?  Where  do  they  terminate 
and  to  what  neurones  are  they  distributed  ?  What  is  the  lemniscus 
and  the  significance  of  the  nuclei  of  the  funiculus  gracilis  and  the 
funiculus  cuneatus?  What  areas  of  the  section  are  occupied  by 
the  cerebello-spinal  axones  ? 

Section  7. — To  pass  through  the  inferior  extremities  of  the  olives 
and  the  point  of 'the  calamus  scriptorius.  Draw,  giving  special 
attention  to  the  following: 

Anterior  median  fissure,  pyramids,  raphe,  calamus  scriptorius  and 
obex;  nuclei  of  funiculus  gracilis  and  of  funiculus  cuneatus,  internal 
arcuate  fibres  and  decussation  of  the  lemnisci;  commissural  nucleus 
of  ala  cinerea,  spinal  tract  of  the  trigeminus  and  the  gelatinous 
substance  containing  its  nucleus  of  termination;  restiform  body, 
external  arcuate  fibres,  lateral  nuclei  and  nucleus  of  the  inferior 
olive. 

What  has  become  of  the  posterior  median  fissure  and  where  is  the 
central  canal?  How  do  the  pyramids  here  differ  from  section  6, 
and  why?  Whence  arise  the  internal  and  external  arcuate  fibres 
and  what  is  their  relation  to  the  lemniscus  ?  Relations  of  the  spinal 
tract  of  the  trigeminus  and  the  distribution  of  axones  arising  from 
its  nucleus  ?  Significance  of  the  decussation  of  the  lemnisci  and  of 
the  pyramids  ?     Look  for  the  nucleus  of  the  hypoglossus. 


14© 


LABORATORY    GUIDE    FOR   HISTOLOGY. 


Section  8.— To  pass  transversely  through  the  middle  of  the  olives. 
Let  the  section  involve  the  overhanging  portion  of  the  cerebellar 
hemisphere  but  avoid  cutting  the  cerebral  hemisphere.  Draw, 
exclusive  of  the  cerebellum,  showing  the  character  of  the  following: 


Fig.  23. — Showing  the  planes  at  which  the  sections  through  the  Rhombencephalon  and 
Mesencephalon  are  to  be  made  (sections  6  to  12  inclusive).— i^row  Morris'  Anatomy  Modified. 

Pyramids,  restiform  body,  inferior  and  accessory  olivary  nuclei, 
spinal  tract  of  trigeminus  with  its  nucleus,  internal  and  external 
arcuate  fibres,  decussation  of  lemnisci,  raphe,  lemniscus  and  gray 
and    white    reticular   formations;    medial   longitudinal   fasciculus. 


SECTIONS    OF    THE    RHOMBENCEPHALON.  141 

root  filaments  of  hypoglossus  and  nucleus  of  hypoglossus;  root 
filaments  of  vagus,  nucleus  ambiguus,  tractus  solitarius  with  its 
nucleus,  nucleus  of  termination  of  the  vagus  and  glossopharyngeus 
(nucleus  alae  cinerea;),  and  the  inferior  or  spinal  part  of  the  nucleus 
of  the  vestibular  nerve. 

What  has  become  of  the  funiculi  gracilis  and  cuneatus  ?  Explain 
the  changes  in  size,  shape  and  position  of  the  restiform  body  and 
state  the  origin,  course  and  destination  of  the  various  axone  systems 
composing  it  at  this  level.  What  is  the  origin,  function  and  extent 
of  the  tractus  solitarius?  Relation  of  the  nucleus  of  termination 
of  the  vagus  to  the  commissural  nucleus?  Nature  of  the  nucleus 
ambiguus  and  to  what  does  it  contribute  fibres?  What  is  the 
medial  longitudinal  fasciculus?  Structure  of  the  nucleus  of  the 
inferior  olive  and  its  relation  to  the  arcuate  fibres?  What, change 
has  occurred  in  the  position  of  Gower's  tract  and  the  descending 
fibres  mingling  with  it?  Character  and  analogy  of  the  arcuate 
nucleus  ?     Origin  and  character  of  the  lining  of  the  rhomboid  fossa  ? 

Section  9. — To  pass  close  to  the  inferior  border  of  the  pons  involving 
the  tip  of  the  superior  extremity  of  the  olive  and  slanting  slightly 
upward,  through  the  entering  root  of  the  acoustic  nerve  and  onward 
through  the  cerebellum.  Draw  the  stained  section  and  complete 
the  drawing  by  adding  the  portion  of  the  cerebellum  (not  included 
in  the  stained  section)  from  the  anterior  of  the  exposed  surfaces  of 
the  cut  specimen.  Show  and  name  especially  the  following: 
Pyramids,  lemniscus,  raphe,  medial  longitudinal  fasciculus,  spinal 
tract  of  trigeminus  with  its  nucleus,  the  arcuate  nucleus,  nucleus 
ambiguus,  nucleus  of  tractus  solitarius  and  root-fibres  of  glosso- 
pharyngeus; restiform  body,  cerebello-olivary  (arcuate)  fibres  and 
olivary  nucleus  (or,  if  section  includes  inferior  edge  of  pons,  nucleus 
of  superior  olive  and  trapezoid  body);  acoustic  medullary  stria, 
acoustic  tubercle,  ventral  nucleus  and  root  of  cochlear  ners'e; 
root  of  vestibular  nerve,  and  medial,  lateral  and  superior  nuclei 
of  vestibular  nerve;  nucleus  and  root- fib  res  of  the  abducens  and 
nucleus  and  root-fibres  of  the  facial  nerve.  Dentate  nucleus, 
nucleus  emboliformis  and  roof  nucleus  of  the  cerebellum;  flocculus, 
inferior  vermis,  uvula  of  vermis,  cerebellar  gyri  and  sulci,  cortical 
substance,  medullary  laminae  and  medullary  body  of  the  cerebellum. 
Why  are  the  pyramids  larger  here  than  in  sections  below  this  level  ? 
Which  of  the  cerebellar  peduncles  are  represented  in  the  section  ? 
The  relation  between  the  inferior  olivary  nucleus  and  the  cere- 
bellum? Ascertain  the  relations  between  the  lateral  and  superior 
nuclei  of  the  vestibular  nerve  and  the  dentate  and  roof  nuclei  of 
the  cerebellum,  and  state  the  functional  significance  of  the  relation. 


142  LABORATORY    GUIDE    FOR   HISTOLOGY. 

What  is  the  course  of  the  acoustic  fibres  contained  in  the  medullary 
striae?  How  are  the  cochlear  nerve,  the  nucleus  of  the  superior 
olive  and  the  trapezoid  body  related  ?  Compare  the  course  of  the 
root-fibres  of  the  facial  nerve,  from  their  nucleus  of  origin  to  their 
exit,  with  those  of  the  abducens.  Where  do  the  fibres  of  the 
intermediate  nerve  arise?  Why  has  the  spinal  tract  of  the  tri- 
geminus and  its  nucleus  increased  in  size  ?  How  are  the  nuclei  of 
the  nerves  of  the  two  sides  of  the  mid-line  associated  with  each  other? 

Section  lo. — To  pass  through  the  pons  at  the  level  of  the  entering 
roots  of  the  trigeminus.  Draw,  giving  special  attention  to  the 
following: 

Tegmental  or  dorsal  part  of  the  pons,  and  basilar  part;  brachium 
conjunctivum,  brachium  pontis,  superficial  and  -deep  fibres  of  the 
pons,  raphe,  and  gray  substance  or  nuclei  of  the  pons;  pyramidal 
fasciculi,  Gowers'  tract  and  reticular  formation;  lemniscus,  medial 
and  lateral,  and  medial  longitudinal  fasciculus ;  the  terminal  nucleus 
and  the  motor  nucleus  (princeps),  and  the  mesencephalic  (descend- 
ing) root  of  the  trigeminus;  anterior  medullary  velum,  ligula  cere- 
belli,  fourth  ventricle,  central  gray  stratum,  and  locus  caeruleus. 
Explain  the  occurrence  of  a  lateral  and  a  medial  lemniscus,  and 
state  the  difference  in  their  functions.  Ascertain  the  course  of  the 
fibres  of  Gowers'  tract  and  give  the  probable  reason  for  their  not 
coursing  in  the  restiform  body.  What  are  the  brachia  conjunctiva  ? 
Explain  the  much  greater  sum  area  of  pyramidal  fibres  here  than 
in  the  levels  below.  Ascertain  the  course  and  termination  of  the 
frontal  and  temporal  pontile  paths.  Explain  the  fact  that  the 
axones  comprising  the  lemnisci  are  much  more  numerous  than 
those  composing  the  funiculi  gracilis  and  cuneatus  of  the  lower 
end  of  the  medulla  oblongata. 

(b)  Sections  oj  the  mesencephalon. 

Section  ii. — To  snip  the  superior  border  of  the  pons  and  pass 
through  the  inferior  colliculi  of  the  corpora  quadrigemina.     Draws 
I  showing  the  following: 

Lamina  quadrigemina  and  tegmentum;  pons  fibres,  peduncle  of 
cerebrum,  substantia  nigra,  lateral  sulcus,  brachia  conjunctiva 
and  their  decussation,  medial  and  lateral  lemnisci  and  nucleus  of 
lateral  lemniscus;  stratum  zonale  and  nucleus  of  inferior  colliculus; 
central  gray  stratum,  mesencephalic  (descending)  root  with  motor 
nucleus  of  trigeminus,  cerebral  aqueduct,  medial  longitudinal 
fasciculus  and  nucleus  and  root  fibres  of  the  trochlear  nerve. 
State  the  course  pursued  by  the  root  fibres  of  the  trochlear  nerve 
from  their  nucleus  of  origin  to  their  exit,  giving  the  locality  and 


SECTIONS    OF    THE    MESENCEPHALON.  1 43 

detail  of  their  decussation.  Where  are  the  pyramids?  What 
portion  of  the  cerebral  peduncle  will  be  occupied  by  the  medial 
lemniscus  in  its  further  course?  What  is  the  significance  of  the 
nucleus  of  the  lateral  lemniscus  and  what  relation  does  this 
nucleus  and  that  of  the  inferior  colliculus  bear  to  the  acoustic 
apparatus  ?  What  is  the  most  probable  path  of  the  axons  of  longer 
course  which  associate  the  nuclei  of  the  cranial  nerves?  What 
descending  cerebral  fibres  are  present  other  than  those  in  the 
cerebral  peduncles? 

Section  12.— To  pass  through  the  region  of  the  emergence  of  the 
oculomotor  nerves  and  just  anterior  to  the  summits  of  the  superior 
colliculi.  The  section  will  involve  the  pulvinar  of  the  thalamus 
and  the  geniculate  bodies  which  are  parts  of  the  prosencephalon. 
Draw,  giving  special  attention  to  the  following: 
Basis  of  peduncle,  substantia  nigra,  medial  longitudinal  fasciculus, 
lemniscus  (medial),  mesencephalic  root  of  the  trigeminus,  central 
gray  stratum  and  aqueduct  of  cerebrum;  nucleus  and  root  filaments 
of  oculomotor  nerve,  nucleus  and  stratum  zonale  of  superior  collic- 
ulus, lateral  geniculate  body,  pulvinar  and  optic  tract;  brachium 
quadrigeminum  inferus,  medial  geniculate  body  and  lateral  reticular 
formation ;  interpeduncular  ganglion,  nucleus  ruber,  and  decussation 
of  the  tegmentum.  Pineal  body,  posterior  commissure  and  stratum 
album  profundum? 

What  is  the  relation  of  the  nucleus  ruber  to  the  brachium  con- 
junctivum  and  its  decussation  ?  Look  up  its  relation  to  the  fascic- 
ulus retroflenus  of  Meynert.  To  what  is  the  name  "substantia 
nigra"  due?  What  is  the  nature,  origin  and  extent  of  the  mesen- 
cephalic root  of  the  trigeminus  and  what  can  now  be  said  of  the 
central  distribution  of  this  nerve?  Ascertain  the  arrangement 
of  the  three  roots  of  the  optic  tract  and  their  relation  to  the  thalamus, 
lateral  geniculate  body,  nucleus  of  the  superior  colliculus,  and 
nucleus  of  the  oculomotor  nerve.  Under  compound  microscope 
examine  the  nucleus  of  the  oculomotor.  What  can  be  said  of  the 
size  and  'arrangement  of  its  cells?  Consult  texts  as  to  its  sub- 
divisions and  the  functional  significance  of  each.  Locate  the  decus- 
sation of  certain  of  the  oculomotor  fibres  and  the  divisions  of  the 
nucleus  from  which  they  arise.  By  what  bundle  is  the  medial 
geniculate  body  connected  with  the  acoustic  apparatus  ?  How 
may  eye  movements  be  associated  with  optic  and  acoustic  impulses  ? 
Head  movements?  What  is  the  origin,  position  in  the  section, 
and  course  of  the  "optic  acoustic  reflex  path?"  Look  up  the 
position  and  significance  of  the  nucleus  (ganglion)  habenula?. 
Nucleus  of  the  posterior  commissure  ? 


144  LABORATORY   GUIDE   FOR   HISTOLOGY. 

(c)  Sections  oj  the   prosencephalon    (telencephalon  and   diencephalon). 

Section  13. — To  pass  through  the  splenium  of  the  corpus  callosum 
and  about  the  middle  of  the  precuneus.  The  plane  may  slant 
toward  the  occipital  pole.  Draw,  giving  attention  to  the  position 
and  appearance  of  the  following  structures: 

Cortical  substance  (cerebral  cortex),  white  substance,  radiation 
of  the  corpus  callosum,  occipito-thalamic  (optic)  radiation,  and  the 
tapetum;  sulcus  of  the  corpus  callosum,  gyrus  and  sulcus  cinguli, 
precuneus,  interparietal  sulcus,  lateral  (Sylvian)  fissure  and  the 
different  gyri  and  the  sulci  separating  them;  the  posterior  horns  of 
the  lateral  ventrical  with  its  bulbus  and  the  glomus  of  its  chorioid 
plexus,  the  calcar  avis  and  collateral  eminence;  collateral  fissure, 
isthmus  of  gyrus  fornicatus,  hypocampal  gyrus  and  fissure,  and 
fusiform  gyrus. 

Identify  the  visual  area  and  state  the  origin  and  distribution  of 
the  axones  comprising  the  occipito-thalamic  radiation.  Of  what 
center  of  cerebral  activity  is  the  precuneus  a  part  ?  Is  the  olfactory 
area  of  the  cortex  represented  in  the  section  ?  How  is  the  collateral 
eminence  produced  ?  Does  the  cortical  substance  vary  in  thickness  ? 
How,  and  where  most? 

Section  14. — -To  pass  through  the  superior  extremity  of  the  posterior 
central  gyrus  and  the  posterior  portion  (pulvinar)  of  the  thalamus. 
Draw,  showing  and  naming  the  following: 

Cortical  gray  substance,  corona  radiata,  radiation  of  corpus  callo- 
sum, corpus  callosum,  and  fornix  with  taenia  fornicis;  inferior  horn 
of  lateral  ventricle  and  central  portion  of  same  with  chorioid  tela 
of  lateral  ventricle,  chorioid  tela  of  third  ventricle  (velum  inter- 
positum),  and  internal  cerebral  veins;  pulvinar  of  thalamus,  cauda 
of  caudate  nucleus,  cerebral  peduncle,  hypothalamic  nucleus, 
internal  capsule,  claustrum,  optic  tract,  hippocarapal  gyrus, 
hippocampal  fissure  the  fimbria  and  fascia  dentata  hippocampi, 
and  the  gyrus  and  sulcus  cinguli. 

What  is  the  corpus  callosum?  What  is  the  relation  of  the  optic 
tract  to  the  pulvinar  thalami  ?  Why  does  the  cauda  of  the  caudate 
nucleus  appear  twice  in  the  section  ?  The  relation  of  the  cerebral 
peduncle  to  the  internal  capsule  and  corona  radiata  ?  Where  is  the 
posterior  commissure  of  the  cerebrum? 

Section  15. — To  pass  through  the  mammillary  body,  the  massa 
intermedia  (middle  commissure),  and  the  anterior  portion  of  the 
paracentral  lobule.  Draw,  giving  special  attention  to  the  following: 
Cortical  substance,  medullary  substance,  radiation  of  corpus  cal- 
losum, corpus  callosum  (trunk),  corona  radiata,  internal  capsule, 


SECTIONS    OF    THE    PROSENCEPHALON. 


145 


basis  of  peduncle,  hypothalamic  nucleus,  ansa  peduncularis,  and 
optic  tract;  septum  pellucidum,  lateral  ventricle  (central  portion  and 
inferior  horn),  and  the  third  ventricle;  the  thalamus  with  its  massa 
intermedia,  laminae  medullares,  ventro-lateral,  medial  and  anterior 
nuclei,  its  stratum  zonale,  taenia,  stria  medullaris,  lamina  affixa 
and  stria  terminalis  thalami;  collateral  fissure,  hippocampal  gyrus, 
digitations  of  hippocampus,  fornix  (corpus),  mammillary  body,  and 
fasciculus  thalamo-mammillaris  to  anterior  nucleus  of  thalamus; 
caudate  nucleus,  vena  terminalis,  lentiform  nucleus  composed  of 


Fig.  24. — Showing  the  planes  at  which  the  sections  of  the  Prosencephalon 
are  to  be  made  (sections  13  to  17). 

putamen  and  globus  pallidus,  amygdaloid  nucleus,  inferior  peduncle 
of  thalamus,  external  capsule,  claustrum  and  and  insula  with  gyri 
insula.  Attach  the  names  to  all  the  important  gyri  and  sulci 
represented  in  the  section,  especially  those  of  the  temporal  lobe. 
What  structures  compose  the  corpus  striatum  ?  "  Basal  ganglia  ?  " 
Where  is  the  lemniscus  and  what  is  its  relation  to  the  hypothalamic 
nucleus  and  the  ventro-lateral  portion  of  the  thalamus?  Give 
the  origin,  course  and  distribution  of  the  fornix  and  the  relation  of 
its  fibres  to  the  nuclei  of  the  mammillary  body.  With  what  sense 
apparatus  is  it  chiefly  concerned  ?     Where  and  what  is  the  pedun- 


146  LABORATORY    GUIDE    FOR   HISTOLOGY. 

culo-mamniillary  fasciculus  ?  What  is  the  position  and  significance 
of  the  hippocampal  commissure  or  "lyre"?  How  many  and  what 
are  the  superior  peduncles  of  the  thalamus  ?  What  comprises  the 
auditory  area  of  the  cerebral  cortex  and  what  are  the  paths  of 
impulses  to  and  from  it  and  the  rhombencephalic  and  mesencephalic 
connections  of  the  acoustic  nerve?  What  is  the  origin  of  the 
claustrum  ? 

Section  16. — To  pass  through  the  optic  chiasma,  the  anterior  com- 
missure and  near  the  pars  libera  of  the  column  of  the  fornix.  Draw, 
especially  showing  the  following: 

Corpus  callosum,  column  of  fornix  (?),  anterior  commissure,  optic 
chiasma,  anterior  perforated  substance,  and  uncus  of  hippocampal 
gyrus;  septum  pellucidum  with  its  cavity  (fifth  ventricle),  the 
anterior  horn  of  the  lateral  ventricle  and  its  chorioid  plexus;  caudate 
nucleus,  internal  capsule,  and  lentiform  nucleus  with  its  putamen, 
medullary  lamina  and  globus  pallidus;  the  gyri  and  sulci  of  the 
temporal  lobe  and  insula. 

In  the  section  of  the  cerebrum  removed  in  making  section  16, 
note  the  triangular  recess,  the  interventricular  foramen,  the  depth 
of  the  third  ventricle  and  the  tuber  cinereum.  What  cerebral 
lobes  are  connected  by  the  anterior  commissure  ?  Where  is  the 
thalamus?  What  are  the  connections  of  the  caudate  and  lenti- 
form nuclei?  In  the  optic  chiasma,  ascertain  the  position  and 
relative  amount  of  true  optic  fibres  comprising  the  commissure, 
and  the  origin,  position  and  siginficance  of  the  inferior  cerebral 
commissure  (Gudden's  commissure).  Where  is  the  superior  cere- 
bral commissure  of  Maynert  ? 

Section  17. — To  pass  through  the  rostrum  of  the  corpus  callosum 
and  the  olfactory  trigone.  Draw,  showing  especially  the  following: 
Genu  of  corpus  callosum,  the  septum  pellucidum,  rostrum  of 
corpus  callosum,  lamina  rostralis,  sulcus  corporis  callosi,  the  two 
longitudinal  stri£e  upon  the  corpus  callosum,  and  the  subcallosal 
gyrus;  olfactory  trigone  (3  striae  evident?),  the  parolfactory  area  and 
parolfactory  sulcus  (?);  the  anterior  horn  of  the  lateral  ventricle, 
caput  of  caudate  nucleus,  frontal  part  of  internal  capsule,  lenti- 
form nucleus  (putamen  only),  external  capsule,  claustrum  and 
insula. 

Why  does  the  lateral  cerebral  fissure  occur  twice  in  the  section? 
What  is  the  relation  of  the  parolfactory  area  to  the  gyrus  rectus  and 
the  olfactory  trigone  ?  What  is  the  destination  of  each  of  the 
olfactory  striae?  Note  that  the  caudate  and  lentiform  nuclei  com- 
prise a  single  ganglionic  mass  separated  in  part  by  the  internal 
capsule. 


MICROSCOPIC    STRUCTURE.  147 

4.  Torn  Preparation. — Lay  out  in  their  serial  order  all  the  drawings  of 

the  sections  of  the  encephalon.  Then  take  the  cerebral  hemisphere, 
detached  in  2,  (a),  and,  beginning  at  the  sulcus  cinguli,  by  means 
of  the  necessary  tearing  with  the  fingers,  and  aided  from  their 
appearances  in  the  different  sections,  obtain  a  clear  conception 
of  the  shape,  course,  interrelationships  and  connections  of  the 
following: 

(a)  The  centrum  semiovale,  the  varying  thickness  of  the  cortical 
gray  substance  (pallium),  the  underlying  white  substance  by  which 
the  gray  substance  of  neighboring  gyri  may  be  associated  (fasciculi 
proprii),  and  that  by  which  the  cerebral  lobes  may  be  associated 
(association  bundles). 

(b)  The  corpus  callosum,  its  splenium,  trunk,  genu  and  rostrum, 
with  the  medial  and  lateral  longitudinal  strise  upon  it;  the 
radiations  of  the  corpus  callosum,  comprising  an  occipital  portion 
(forceps  major  of  the  two  hemispheres  combined),  a  superior  and 
lateral  radiation  to  the  parietal  and  temporal  lobes,  and  a  frontal 
radiation  (forceps  minor). 

(c)  The  shape  of  the  lateral  ventricles,  separated  by  the  septum  pellu- 
cidum,  connected  with  the  third  ventricle  and  with  each  other 
by  the  interventricular  foramen,  and  each  consisting  of  an  anterior 
horn,  a  central  part,  a  posterior  horn  and  an  inferior  horn;  the 
central  part  and  inferior  horn  containing  the  chorioid  plexus. 

(d)  The  anterior  commissure  connecting  the  temporal  lobes  and 
joined  by  commissural  fibers  from  the  medial  olfactory  stria. 

(e)  The  hippocampus,  the  commissure  of  the  hippocampus;  the  fornix, 
consisting  of  the  crus,  body  and  columns  with  pars  libera  and  pars 
tecta;  the  mammillary  body,  the  thalamo-mammillary  fasciculus 
and  the  anterior  tubercle  of  the  thalamus. 

(f)  The  shape  of  the  caudate  nucleus  and  its  relation  to  the  lentiform 
nucleus. 

(g)  The  shape  of  the  thalamus  and  its  connection  with  the  optic  tract, 
the  cerebral  peduncle  and  the  cerebral  cortex.  What  is  the  relation 
of  the  stria  medullaris  thalami  to  the  habenular  commissure  and 
habenular  nuclei? 

(h)  The  internal  capsule  consisting  of  frontal  portion,  genu,  parietal 
portion  and  occipital  portion,  and  continuous  with  the  cerebral 
peduncle,  pyramids  and  lemniscus  below,  and  with  the  corona 
radiata  to  the  cerebral  cortex  above.  What  is  the  relation  of  its 
genu  to  the  stria  terminalis  thalami? 

5.  Microscopic  structure. 

(a)  Under  the  compound  microscope,  examine  a  transverse  (frontal) 
section  taken  at  the  level  of  the  mammillarv  bodv  and  invohanfii:  the 


148  LABORATORY    GUIDE    FOR   HISTOLOGY. 

basis  pedunciili,  thalamus  and  corpus  striatum  only,  and  stained  by 
.the  Weigert  method  and  Upson's  carmin.  Sketch  under  an  en- 
largement of  about  two  diameters,  indicating  the  abundance  and 
arrangement  of  the  cell-bodies  and  the  occurrence  and  detailed 
arrangement  of  the  white  substance.  Note  the  continuation 
between  the  medullary  laminae,  stratum  zonale  and  stria  terminalis 
of  the  thalamus  and  the  genu  of  the  internal  capsule.  Explain 
the  presence  of  the  optic  tract  in  the  section.  Which  nuclei  of  the 
thalamus  are  represented  and  to  which  of  these  is  the  fasciculus 
thalamo-mammillaris  distributed?  What  is  the  course  and 
significance  of  the  fasciculus  pedunculo-mammillaris  ?  Note  the 
position  of  the  hypothalamic  nucleus  and  state  its  functional  relation 
to  the  lemniscus  and  internal  capsule.  By  what  is  the  name  of  the 
lentiform  nucleus  suggested  ?  Globus  pallidus  ?  What  differences 
of  shape  and  size  are  to  be  noted  in  the  cell-bodies  of  the  various 
nuclei  in  the  section  ?  By  what  paths  and  with  what  regions  of  the 
cerebral  cortex  are  the  nuclei  of  the  corpus  striatum  connected? 
(b)  Somesthetic  Area  of  Cerebral  Cortex. — ^From  the  same  block  of  cere- 
bral cortex,  taken  from  either  the  precentral  or  postcentral  gyrus,  two 
ventrical  sections  are  furnished,  one  stained  for  the  cell-bodies 
alone  and  the  other  by  the  Weigert  method  for  the  nerve-fibres. 
Under  the  same  magnification,  draw  two  vertical  strips  side  by  side, 
one  strip  from  each  section,  showing  the  cell-strata  and  the  ar- 
rangement of  the  fibres  as  follows: 

Cell-strata : 

(i)  Superficial  cell-stratum, 

(2)  Stratum  of  small  pyramidal  cells, 

(3)  Of  large  pyramidal  cells, 

(4)  Of  polymorphic  cells,  and 

(5)  Of  fusiform  cells. 

Fibers : 

(i)  Plexus    of  molecular  layer, 

(2)  Submolecular  plexus, 

(3)  Great  pyramidal  plexus, 

(4)  Plexus  of  polymorphic  cell  stratum,  and 

(5)  White  substance  continuous  into  fibroe  propriae  (arcuatae)  and 
corona  radiata. 

What  are  the  chief  components  and  significance  of  the  interstratal 
plexuses  ?  Whence  arise  the  different  axones  bearing  impulses  to 
the  cells?  Which  cell-bodies  give  origin  to  the  pyramids  of  the 
medulla  oblongata  and  descending  cerebrospinal  fasciculi  ?  Rela- 
tive abundance  of  giant  pyramidal  cells  in  the  section  and  signifi- 
cance of  their  being  more  abundant  in    the  precentral  than  in  the 


SPINAL    REFLEX    PATHS.  1 49 

postcentral  gyrus  ?  State  briefly  the  general  differences  in  the  cell- 
strata  of  the  cortex  of  the  optic  area,  the  auditory  area,  the  uncus 
of  the  hippocampus  and  of  the  general  structure  of  the  so-called 
"association  (psychic)  centers." 

(c)  Make  a  careful  drawing  of  a  strip  through  the  thickest  (ventral) 
portion  of  a  transverse  section  of  the  olfactory  bulb,  using  either  a 
successful  Golgi  or  a  Weigert  preparation.  Name  the  strata  present 
and  compare  with  the  other  regions  of  the  cerebral  cortex  studied. 
Significance  of  the  glomeruli?  Which  cells  give  origin  to  the 
olfactory  tracts?  Origin  and  more  accepted  destinations  of  the 
olfactory  striae?  Existence  of  an  olfactory  ventricle?  Origin  of 
the  latter  and  its  persistence  in  comparative  anatomy  ? 

(d)  Review  the  varieties  of  cell-bodies  and  the  number  and  order  of  the 
cell-strata  of  the  cerebellar  cortex  studied  in  the  histology  of  the 
nervous  system,  ascertaining  from  texts  the  functional  inter- 
relation of  the  various  cells  and  the  variety  and  origin  of  the  axones 
distributing  impulses  to  them,  and  then  construct  a  schematic 
representation  of  the  architecture  of  the  cerebellar  cortex. 
Considering  the  abundant  connections  of  the  vestibular  nerve  with 
the  gray  substance  of  the  cerebellum,  what  significance  may  be  in- 
ferred of  the  arrangement  of  the  cerebellar  gyri  and  the  dendrites 
of  the  Purkinje  cells?     Other  functions  of  the  cerebellum? 

III.  RECONSTRUCTIONS. 

Lay  in  their  serial  order  all  the  17  drawings  made  of  the  gross  sections  of 
the  spinal  cord,  rhombencephalon  and  cerebrum,  study  them  carefully  with 
reference  to  the  various  structures  appearing  consecutively  in  them,  and,  with 
the  aid  of  descriptive  texts,  construct  diagrams  of  the  central  nervous  system 
illustrating  the  following  of  the  principal  conduction  pathways  (systems  of 
neurone  chains). 

A.  Diagram  of  the  Spinal  Reflex  and  the  Cerebrospinal  Pathways. 
I.  Spinal  reflex  paths. 

(a)  Terminal  corpuscle  or  "free  termination"  of  peripheral  process 
of  T-fibre  of  spinal  ganglion  neurone. 

(b)  Afl'erent  (sensory)  axone  in  trunk  of  spinal  nerve. 

(c)  Cell-body  of  origin  in  spinal  ganglion. 

(d)  Dorsal  root  of  spinal  nerve. 

(e)  Bifurcation  in  spinal  cord  with  ascending  and  descending  branches 
giving  off  collaterals  and  terminating — 

(i)  Directly  upon  cell-bodies  of  ventral  horn  of  same  side  in  same 

level  of  spinal  cord. 
(2)  Upon  Golgi  cell  of  type  II,  the  axone  of  wliich  terminates  upon 

ventral  horn  cells. 


150  LABORATORY   GUIDE   FOR   HISTOLOGY. 

(3)  Upon  ventral  horn  cells  of  opposite  side,  the  terminal  branch  or 
callateral  crossing  the  mid-line  by  way  of  either  the  anterior  or 
posterior  white  commissure. 

(4)  Upon  cell-body  giving  origin  to  axone  of  fasciculus  proprius  of 
same  side,  the  branches  of  which  axone  terminate  upon  ventral 
horn  cells  in  levels  of  spinal  cord  other  than  the  level  at  which 
the  dorsal  root  (afferent  axone)  enters. 

(f)  Ventral  horn  cells  of  same  and  opposite  sides  giving  axones  to  ventral 
roots  and  trunks  of  spinal  nerves  directly  to  striated  muscle-fibres 
or,  indirectly,  through  the  mediation  of  sympathetic  neurones,  to 
smooth  muscle-fibres  and  gland  cells. 

2.  Cerebrospinal  path. 

(a)  Neurone  of  the  first  order — ascending: 

(i)  Terminal  sensory  corpuscle  of  peripheral  process  of  T-fibre  in 
trunk  of  spinal  nerve. 

(2)  Cell-body  with  T-fibre  in  spinal  ganglion. 

(3)  Dorsal  root  of  spinal  nerve. 

(4)  Bifurcation  in  spinal  cord  with  both  descending  branch  and 
collaterals  above  and  below  bifurcation  terminating  upon  cell- 
bodies  for  spinal  "reflex"  paths  as  above. 

(5)  Ascending  branch  of  bifurcation  passing  in  fasciculus  gracilis 
or  fasciculus  cuneatus  to  termination  in  medulla  oblongata  upon 
cell-bodies  of — 

(b)  Neurone  of  second  order — ascending: 

(i)  Cell-body  in  nucleus  of  fasciculus  gracilis  or  of  fasciculus  cunea- 
tus. 

(2)  Internal  arcuate  fibres. 

(3)  Decussation  of  lemniscus. 

(4)  Lemniscus  of  opposite  side. 

(5)  Medial  lemniscus  to  termination  in  diencephalon  upon  cell- 
bodies  of — 

(c)  Neurone  of  the  third  order — ascending: 

(i)  Cell-body  of  hypothalamic  nucleus  or  ventro-lateral  nucleus  of 
thalamus. 

(2)  Internal  capsule,  anterior  part  of  its  occipital  portion. 

(3)  Corona  radiata,  fronto-parietal  portion,  to  termination  in  somes- 
thetic  area  of  cerebral  cortex  (telencephalon)  upon  cell-bodies  of — 

(d)  Descending  system  of  neurones: 

(i)  Giant  pyramidal  cells  of  somesthetic  area  (pre-  and  post-central 
gyri,  the  former  chiefly). 

(2)  Corona  radiata,  fronto-occipital  portion. 

(3)  Internal  capsule,  genu  and  anterior  part  of  occipital  portion. 

(4)  Cerebral  peduncle. 


CEREBRAL    PATHS    OE    CRANIAL    NERVES.  I51 

(5)  Pyramid  of  medulla  oblongata. 

(6)  Decussation  of  pyramids. 

(7a)  Lateral  cerebrospinal  fasciculus  of  opposite  side  of  spinal  cord, 

and 
(7b)  Ventral  cerebrospinal    fasciculus    with  gradual   decussation   to 
opposite  side  of  spinal  cord  in  cervical  and  upper  thoracic  seg- 
ments, to  terminate  in  ventral  horn  upon  cell-bodies  of — 
(e)  Efferent  spinal  neurones: 
(i)  Ventral  horn  cells. 

(2)  Ventral  root  of  spinal  nerve. 

(3)  Spinal  nerve  directly  to  termnation  upon  striated  muscle-fibre, 
or,  upon  cell-body  of  sympathetic  neurone,  the  axone  of  which 
terminates  upon  smooth  muscle-fibre  or  gland  cell. 

B.  Diagram  of  Principal  Pathways  of  the  Cranial  Nerves  Exclusive 
of  those  of  Special  Sense. 

1.  "Reflex'' paths. 

(a)  Cell-bodies  in  ganglia  of  origin  of  sensory  portions  of  vagus,  glos- 
sopharyngeus,  facial  and  trigeminus  with  peripheral  arborizations 
and  peripheral  branches  of  T-fibres  of  same. 

(b)  Central  branches  of  T-fibres  of  same  into  medulla  oblongata  where, 
bifurcated  and  unbifurcated,  these  branches  send  collaterals  and 
terminal  twigs  to  nuclei  of  termination  (chiefly)  of  the  respective 
cranial  nerves,  and  some  to  nuclei  of  origin  of  motor  cranial  nerves 
and  motor  portions  of  mixed  nerves. 

(c)  Cell-bodies  of  nuclei  of  termination  give  axones  to  motor  nuclei 
of  nerves  of  same  side,  and,  through  reticular  formation  and  raphe, 
to  motor  nuclei  of  opposite  side  of  same  and  of  dift'erent  levels, 
above  and  below,  the  axones  to  more  distant  nuclei  coursing  by 
way  of  medial  longitudinal  fasciculus. 

(d)  Axones  from  nuclei  of  origin  of  motor  nerves  and  motor  portions  of 
mixed  cranial  nerves  pass  in  these  nerves  to  termination  in  respective 
tissues  supplied,  or  upon  cell-bodies  of  sympathetic  neurones  in 
respective  chains  concerned.  Let  the  trigeminus,  by  way  of  its 
spinal  tract,  and  the  vagus  and  glossopharyngeus  by  way  of  the 
solitary  tract,  distribute  impulses  to  the  ventral  horn  cells  giving 
origin  to  the  ventral  roots  of  upper  cervical  nerves. 

2.  Cerebral  paths  of  cranial  nerves. 

(a)  Ganglion  cells  of  origin  and  peripheral  and  central  branches  of 
T-fibres  of  sensory  portions  of  the  vagus,  glossopharyngeus,  facial 
and  trigeminus. 

(b)  Nuclei  of  terminations  of  central  branches  (bifurcated  and  unbi- 
furcated) in  medulla  oblongata. 


152  LABORATORY    GUIDE    FOR    HISTOLOGY. 

(c)  Axones  from  respective  nuclei  of  termination  pass  to  reticular 
formation  and  medial  lemniscus  of  same  and  (chiefly)  of  opposite 
side  and  ascend  to  their  termination  upon  cells  of  hypothalmic 
nucleus  and  lateral  nucleus  of  thalamus. 

(d)  Axones  from  cells  of  latter  nuclei  ascend  in — 

(i)  Internal  capsule,  anterior  part  of  occipital  portion; 

(2)  Corona  radiata,  fronto-parietal  portion, 

(3)  To  terminate  in  somesthetic  area  of  cerebral  cortex. 

(e)  Axones  of  pyramidal  cells  of  somesthetic  area  descend  in — 
(i)   Corona  radiata,  fronto-parietal  portion; 

(2)  Internal  capsule,  genu  chiefly; 

(3)  Cerebral  peduncle; 

(4)  "Accessory  lemniscus"  to  terminate  about, 

(5)  Cells  of  nuclei  of  origin  of  motor  cranial  nerves  and  of  motor 
portions  of  mixed  cranial  nerves. 

(f)  Axones  from  these  nuclei  pass  in  the  respective  nerves  to  the  muscles 
supplied,  or  terminate  in  sympathetic  gangha. 

C.  Diagram  of  Spinal  and   Cerebral   Pathways  Involving  the  Cere- 
bellum. 

I.  Cerebello-spinal  paths. 

(a)  Peripheral  sensory  fibres,  spinal  ganglia  and  dorsal  roots  of  spinal 
nerves. 

(b)  Bifurcating  dorsal  root  fibres  in  spinal  cord  give  collaterals  and 
terminal  twigs  to  the  cell-bodies  of  the  nucleus  dorsahs  (Clark's 
column)  and  to  cell-bodies  (Stilling's  nucleus)  in  the  ventro-lateral 
neighborhood  of  the  nucleus  dorsalis. 

(ci)  Fibres  from  nucleus  dorsalis  ascend — 

(i)  As  the  cerebello-spinal  fasciculus  (direct  cerebellar  tract); 

(2)  Into  restiform  body  (inferior  cerebellar  peduncle); 

(3)  Joined  in  medulla  oblongata  by  external  arcuate  fibres  (crossed 
and  uncrossed)  arising  from  nuclei  of  funiculus  gracilis  and 
funiculus  cuneatus,  which  fibres  make  possible  a  second  con- 
nection between  sensory  spinal  neurones  and  the  cerebellum; 

(4)  Joined  in  medulla  oblongata  by  fibres  arising  in  the  nuclei  of 
termination  of  sensory  portions  of  vagus,  glossopharyngeus, 
vestibularis  and  trigeminus. 

(5)  All  these  fibers  pass  through  white  substance  of  cerebellum  to 
terminate  about  cell-bodies  in  dentate  nucleus,  nucleus  fastigii 
(those  from  nucleus  of  vestibularis  especially),  and  cerebellar 
cortex  (vermis). 

(c2)  Axons  from  cells  ventro-lateral  to  nucleus  dorsalis  ascend — 
(i)  As  Gowers'  tract  in  spinal  cord; 
(2)  Through  reticular  formation  of  medulla  oblongata  and  pons; 


CEREBELLO-CEREBRAL    PATHWAYS.  I  53 

(3)  Turn  back  in  anterior  medullary  velum  and  brachium  conjunc- 
tivum,  enter  white  substance  of  cerebellum  and  pass  to  termi- 
nation in  cerebellar  cortex  (vermis  chiefly)  and  dentate  nucleus, 
(d)  Fibres  from  nucleus   fastigii    (chiefly),  from  dentate    nucleus  and 
from  Purkinje  cells  of  cerebellar  cortex  (vermis),  descend  in  the 
intermediate  and  anterior  marginal  fasciculi  to  terminate  about 
the  ventral  horn  cells  of  the  spinal  cord. 

Indirectly  connecting  the  spinal  cord  with  the  cerebellum  is  the 
pathway  arising  from  the  nucleus  ruber  of  the  opposite  side  and 
decussating  in  the  mesencephalon,  and  that  arising  from  the  nucleus 
of  termination  of  the  vestibulat  nerve  of  the  same  side,  and  descend- 
ing in  the  intermediate  fasciculus  to  be  distributed  to  the  gray 
substance  of  the  spinal  cord.  Likewise,  the  olivary  fasciculus  of 
Helweg  is  an  indirect  cerebellar  connection  since  the  inferior  olives 
are  nuclei  chiefly  concerned  with  the  cerebellum. 
2.  Cerebello-cerebral  pathways. 

^a)  Fibres  from  the  dentate  nucleus  and  Purkinje  cells  of  cerebellar 
cortex  (vermis  chiefly)  ascend  in  brachium  conjunctivum,  cross  to 
opposite  side  in  decussation  of  brachia  conjunctiva,  and  terminate 
in  nucleus  ruber  and  (chiefly)  in  lateral  nucleus  of  thalamus. 

(b)  Fibres  from  these  two  nuclei  (i)  ascend  in  middle  third  of  internal 
capsule  and  fronto-parietal  part  of  corona  radiata  to  terminate  in 
somesthetic  area  of  cerebral  cortex  and  adjoining  cortex  of  frontal 
lobe,  and  (2)  pass  by  way  of  inferior  peduncle  of  thalamus  to  cortex 
of  temporal  lobe  (superior  and  middle  gyri). 

(c)  Fibres  from  pyramidal  cells  of  somesthetic  area  descend  through 
corona  radiata,  internal  capsule,  and  cerebral  peduncle  to  nuclei 
of  pons  and  to  arcuate  nuclei  of  same  and  opposite  sides. 

(d)  Fibres  from  cortex  of  frontal  lobe  descend,  as  frontal  pontile  path, 
through  frontal  parts  of  corona  radiata  and  internal  capsule,  and 
medial  part  of  cerebral  peduncle  to  nuclei  of  pons. 

(e)  Fibres  from  cortex  of  temporal  lobe,  as  temporal  pontile  path,  pass 
under  lenticular  nucleus  into  occipital  portion  of  internal  capsule 
and  outer  portion  of  cerebral  peduncle,  to  nuclei  of  pons. 

(f)  Cells  of  nuclei  of  pons  give  origin  to  fibres  which  pass  in  brachium 
pontis  to  cortex  of  cerebellar  hemisphere  of  the  side  opposite  that  of 
the  cerebral  hemisphere  concerned. 

D.  Diagram  of  Pathways  of  the  Auditory  Apparatus. 

I.   Vestibular  portion. 

(a)  Short  peripheral  processes  from  the  cells  of  the  vestibular  ganglion 
pass  to  termination  in  the  utricular  and  the  three  ampullar  branches; 

(b)  Central  processes  of  the  cells  of  this  ganglion  (the  vestibular  nerve) 
enter  medulla  oblongata  to  terminate  upon  cells  of  the  lateray 


154  LABORATORY    GUIDE    FOR   HISTOLOGY. 

medial  and  superior  vestibular  nuclei  and  the  nucleus  of  the  descend- 
ing vestibular  root, 
(c)  Fibres  arising  from  the  vestibular  nuclei  are  distributed  as  follows: 
(i)  From  the  lateral  and  superior  nuclei  to  the  nucleus  fastigii  of  the 
opposite   side   and   to   the   dentate   nucleus   and   cortex   vermis 
(cerebellar  connection). 

(2)  From  the  superior  and  medial  nuclei,  by  way  of  the  medial 
longitudinal  fasciculus,  to  the  nucleus  of  origin  of  the  "eye- 
muscle"  nerves  of  the  same  and  opposite  side. 

(3)  From  the  lateral  nucleus  and  nucleus  of  the  descending  root, 
through  the  reticular  formation,  into  the  lateral  funiculus  of  the 
spinal  cord  (spinal  connection). 

2.  Cochlear  portion. 

(a)  Short  peripheral  processes  of  bipolar  cells  of  spiral  ganglion  term- 
inate upon  the  neuro-epithelial  cells  of  the  organ  of  corti. 

(b)  Central  processes  of  these  cells  combine  to  form  the  cochlear 
nerve  and  pass  to  medulla  oblongata  to  terminate  upon  cells  of 
ventral  and  dorsal  nuclei  of  cochlear  nerve. 

(c)  Fibres  arising  from  cells  of  dorsal  nucleus  of  cochlear  nerve  pass 
around  outer  side  of  restiform  body  and,  as  striae  medulares  acustici, 
pass  medianward  in  floor  of  fourth  ventricle  to  mid-line,  then 
ventralward  into  tegmentum  where  they  decussate  and  join 
trapezoid  body  to  lateral  lemniscus  of  opposite  side  in  w^hich  they 
pass  to  terminate  in  nucleus  of  inferior  colliculus  and  medial 
geniculate  body  of  that  side. 

(d)  Fibres  from  ventral  nucleus  of  cochlear  nerve  pass  ventrally 
medianward,  some  to  terminate  in  superior  olivary  nucleus  of  same 
side,  others,  through  trapezoid  body  and  lateral  lemniscus,  to 
terminate  about  cells  of  nucleus  of  superior  olive,  of  lateral  lemnis- 
cus, of  medial  geniculate  body,  and  of  inferior  colliculus  of  opposite 
side. 

(e)  Fibres  from  superior  oUvary  nuclei  of  both  sides,  and  from  nucleus 
of  lateral  lemniscus,  terminate,  some  in  nucleus  of  inferior  colli- 
culus, some  in  medial  geniculate  body,  and  probably  some,  uninter- 
rupted, pass  to  termination  in  cortex  of  temporal  lobe. 

(f)  Fibres  from  medial  geniculate  body  and  inferior  colliculus  pass 
into  internal  capsule  and  through  temporal  part  of  corona  radiata 
to  terminate  in  cortex  of  superior  temporal  gyrus  (middle  third 
chiefly). 

(g)  Certain  fibres  from  superior  olivary  nucleus  pass  dorsalward  to 
terminate  upon  cells  of  the  nucleus  of  the  abducens  (peduncle  of 
superior  olive)  and,  by  way  of  medial  longitudinal  fasciculus,  to 
terminate  in  other  nuclei  of  motor  cranial  nerves. 


PATHWAYS    OF    OLFACTORY    APPARATUS.  155 

E.  Diagram  of  Principal  Pathways  of  the  Optic  Apparatus. 

1.  Short,  "peripheral"  processes  of  bipolar  cells  of  retina  terminate 
upon  neuro-epitheHal  layer,  the  rods  and  cones,  and  their  central  proc- 
esses terminate  in  conjunction  with  dendrites  of  ganglion  cells  of  retina. 

2.  Fibres  arising  from  ganglion  cells  form — 

(a)  Optic  stratum  of  retina. 

(b)  Opitic  nerve. 

(c)  Optic  chiasma;  fibres  from  nasal  side  of  retina  decussate  in  chiasma 
and  fibres  from  lateral  side  of  retina  continue  on  same  side. 

(d)  Optic  tract,  which  terminates  in  three  roots :  One  upon  cells  in 
pulvinar  of  thalamus;  one  in  lateral  geniculate  body,  and  one 
passes  under  medial  geniculate  body  to  nucleus  of  superior  coUic- 
ulus. 

3.  Fibres  from  nucleus  of  superior  colliculus  pass  ventrally  to  nuclei  of 
oculomotor  and  trochlear  nerves  of  same  and  opposite  sides  and,  by 
way  of  medial  longitudinal  fasciculus,  to  nuclei  of  abducens,  and  these 
three  nuclei  send  fibres  to  the  muscles  producing  eye  movements. 

4.  Fibres  from  cells  of  lateral  geniculate  body  and  pulvinar  pass  through 
occipital  portion  of  internal  capsule  and  occipito-thalamic  radiation  to 
terminate  in  cortex  of  occipital  lobe  (gyri  bordering  calcarine  fissure, 
chiefly). 

5.  Fibres  from  visual  area  of  cortex  descend  through  occipito-thalamic. 
radiation  and  internal  capsule  to  terminate  in  nucleus  of  superior  collic- 
ulus (occipito-mesencephalic  fasciculus),  and,  by  way  of  neurones  of 
this  nucleus,  distribute  cortical  impulses  to  nuclei  of  nerves  for  eye 
movements. 

6.  Fibres  from  nucleus  of  superior  colliculus  and  pulvinar  enter  medial 
longitudinal  fasciculus  of  same  and  opposite  sides  and  descend  into 
ventral  and  lateral  funiculi  of  spinal  cord  to  terminate  upon  cells  of  its 
gray  substance.  Fibres  from  superior  colliculus  decussate  in  "optic- 
acoustic  reflex  path"  in  mesencephalon. 

F.  Diagram  of  Principal  Pathways  of  the  Olfactory  Apparatus. 

1.  Short  "peripheral"  processes  of  bipolar  cells  in  olfactory  region  of 
nasal  epithelium  terminate  in  "olfactory  hairs,"  and  centrally  directed, 
non-medullated  processes,  the  olfactory  nerve,  pass  through  lamina 
cribrosa  of  ethmoid  bone  to  terminate  in  glomerular  layer  of  olfactory 
bulb  in  conjunction  with  dendrites  of  mitral  cells. 

2.  Fibres  arising  from  mitral  cells  form  olfactory  tract  which  passes 
backward  and  divides  into — 

(a)  Medial  olfactory  stria  through  which  fibres  pass  to  terminate  (i) 
in  parolfactory  (Broca's)  area,  (2)  in  subcallosal  gyrus,  and  (3), 
byway  of  anterior  cerebral  commissure,  in  olfactory  bulb  of  opposite 
side. 


156  LABORATORY    GUIDE    FOR    HISTOLOGY. 

(b)  Intermediate  olfactory  stria  which  disappears  in  anterior  per- 
forated substance. 

(c)  Lateral  olfactory  stria  which  terminates  (i)  in  anterior  perforated 
substance  and,  chiefly,  in  uncus,  in  hippocampal  gyrus  proper,  and 
in  gyrus  cinguli  (olfactory  area). 

3.  Fibres  arising  from  cells  in  uncus  and  hippocampal  gyrus  comprise — 

(a)  The  cingulum  (in  part),  by  which  the  cortex  of  the  gyrus  cinguli, 
subcallosal  gyrus,  and  anterior  perforated  substance  are  associated. 

(b)  The  hippocampal  commissure  (in  part),  through  which  they  pass 
to  terminate  in  the  olfactory  area  of  the  opposite  side. 

(c)  The  fornix,  which  terminates  (i)  in  small  part  upon  cells  in  mam- 
millary  body  of  same  and  opposite  side;  (2)  the  remainder,  ac- 
companied by  fibres  arising  in  the  mammillary  body,  passes  in  the 
thalamo-mammillary  fasciculus  to  terminate  in  the  anterior  nuclei 
of  the  thalami. 

4.  Fibres  arising  in   the  mammillary  body,  and  probably  some   from 

fornix  direct,  pass  by  way  of  the  pedunculo-mammillary  fascic- 
ulus into  the  cerebral  peduncle  and  descend  to  terminate  in  the 
nuclei  of  the  mesencephalon  and  medulla  oblongata. 

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THE  ORGANS  OF  SPECIAL  SENSE  (ORGANA  SENSUUM). 

(twelfth  paper.) 

I.     THE  SKIN  (INTEGUMENTUAl  COMMUNE),  THE  ORGAN 

OF  TOUCH. 

A.  Macroscopic  Features. 

1.  With  dissecting  lens  examine  the  palm  of  the  hand,  the  volar  surface 
of  the  thumb  or  index  finger,  the  dorsal  surface  of  the  hand  and  the 
skin  of  the  fore-arm.  What  differences  are  to  be  noted  in  the  different 
localities  ?  How  is  the  surface  modified  immediately  about  the  insertion 
of  the  hairs  (pili)  ?  Pinch  up  the  skin  of  the  different  localities  and 
note  apparent  differences  as  to  thickness. 

2.  Clean  a  side  and  dry  it  thoroughly,  then  carefully  take  an  impres- 
sion of  the  volar  surface  of  the  thumb  upon  it  and  examine  under  low 
magnification.  Draw  a  small  area  showing  crista  and  sulci  cutis  and 
the  openings  of  the  ducts  of  the  sweat-glands  (pori  sudoriferi).  Where 
do  the  latter  open  with  reference  to  the  former?  Are  the  summits 
of  the  cristae  perfectly  smooth? 

What  is  the  average  area  of  the  skin?  Weight?  Difference  in  thick- 
ness on  dorsal  and  ventral  surfaces  of  the  body  ? 

B.  Microscopic. 

I.  From  a  stained  vertical  section  of  the  skin  of  the  volar  surface  of  the 
finger,  make  a  drawing  under  low  power  showing  the  peculiarities  and 
inter-relations  of  the  following  components: 

(a)  Epidermis. 

(i)  Stratum  germinativum  (malpighian  layer)  composed  of  cells 
hexagonal  in  section  and  a  basal  layer  of  columnar  cells  resting 
upon  a  basement  membrane. 

(2)  Stratum  granulosum  composed  of  two  or  three  layers  of  lozenge- 
shaped  cells  containing  deeply  staining  granules. 

(3)  Stratum  lucidum,  a  thin  transparent  layer  of  cells  not  differ- 
entially straining. 

(4)  Stratum  corneum,  a  thick  layer  in  which  the  cytoplasm  and 
nucleus  has  been  exhaused  in  the  production  of  horny  envelopes 
and  scales  and  through  which  the  ducts  of  the  sweat-glands 
pursue  markedly  spiral  courses. 

(b)  Corium  (dermis,  cutis). 

(i)  Stratum  pajnllare  (tunica  propria),  sending  numerous  and 
variable  finger-like  papillae  into  the  stratum  germinativum  of  the 
epidermis. 

160 


THE    HAIR.  l6l 

(2)  Stratum  reticulare,  arbitrarily  separated  from  stratum  papillare, 
containing  looser  connective  tissue,  larger  blood-vessels  and 
tortuously  running  ducts  of  sweaff-glands  which  pass  to  the 
peculiarly  coiled  bodies  of  their  glands  situated  in  the  tela  sub- 
cutanea  and  among  the  masses  of  adipose  tissue,  sections  of  blood- 
vessels and  nerve  twigs. 
2.  From  the  same  section  draw  under  high  power  (a)  two  or  three  cells 
from  each  of  the  strata  of  the  epidermis,  showing  their  shape,  detailed 
structure  and  indicating  their  staining  characters,  and  (b),  draw  a  papilla 
corii  covered  by  the  basal  layer  of  columnar  epidermal  cells  and  con- 
taining a  ^Meissner's  corpuscle  (corpusculum  tactus).  WTiat  are  the 
peculiarities  of  the  cells  of  the  stratum  lucidum  producing  the  appear- 
ance meriting  the  name?  Xote  the  apparent  intercellular  bridges  in 
the  Malpighian  layer  meriting  the  name  '"prickle  cells."  In  which 
stratum  may  eAidences  of  cell  di\'ision  be  found?  Trace  the  changes 
by  which  the  cells  of  the  stratum  germinati\-um  become  transformed 
into  the  superficial  scales  of  the  stratum  corneum.  \Miat  is  the 
structure  of  ^^leissner's  corpuscle?  Make  a  diagrammatic  reconstruc- 
tion of  a  sweat-gland  with  its  entire  duct.  Look  through  the  tela  sub- 
cutanea  for  sections  of  Pacinian  corpuscles  (corpuscula  lamellosa). 
3.  Compare  the  section  from  the  volar  surface  of  the  finger  with  a 
similar  section  of  the  general  skin  of  the  bcdy  and  enumerate  the  struc- 
tural and  quantitative  differences  bet^veen  the  two.  ^^^lich  layer  of 
cells  bears  the  pigment  of  the  skin  of  the  negro  ?  Where  are  the  papillae 
corii  more  poorly  developed  and  what  can  be  said,  in  general,  of  the 
result  of  age  upon  their  height?  AMien  may  the  tela  subcutanea  be 
called  paniculus  adiposus  ?  Give  two  causes  of  the  color  of  the  skin  of 
white  races. 

C.  Appendages  of  the  Skin. 
I.  The  hair  (pilus). 

(a)  Gently  stroke  the  hairs  of  the  back  of  the  hand  and  short  hairs  of 
the  scalp  and  note  the  extreme  sensitiveness  indicated.  Xote  the 
various  angles  at  which  the  hairs  are  inserted  on  the  back  of  the 
hand  and  wrist.  Gently  pull  a  single  hair  of  the  wrist  sufficiently 
to  lift  the  epidermis  about  its  insertion  and  carefully  observe  the 
region  with  a  hand  lens.  Extract  a  hair,  mount  in  glycerine, 
and  examine  the  extracted  end  with  the  compound  microscope, 
identifying  its  scapus,  radix  and  bulbus.  Appearance  of  peri- 
pheral end?  From  what  regions  of  the  surface  of  the  body  are 
hairs  absent?  What  is  the  general  law  for  the  direction  of  the 
hairs  of  the  body  ? 

(b)  From  each  of  two  stained  sections  of  the  human  scalp,  one  passing  . 
longitudinally  and  the  other  transversely  through  the  hairs  and 


1 62  LABORATORY    GUIDE    FOR    HISTOLOGY. 

hair  follicles,  make  a  drawing  illustrating  the  structure  and  inter- 
relations of  the  parts  of  a  hair  and  its  follicle  as  they  appear  cut  in 
the  two  planes.  (Note  that  the  follicle  results  from  an  invagination 
of  the  skin  and  that  it  therefore  consists  of  an  epidermal  sheath 
and  a  sheath  of  connective  tissue  (corium),  the  layers  of  which  two 
sheaths  correspond  to  the  strata  of  the  epidermis  and  corium.  In 
the  drawing  of  the  longitudinal  section,  include  a  sebaceous  gland, 
showing  its  general  structure  and  the  relation  of  its  duct  to  the 
follicle  and  the  hair.  Determine  the  significance  and  show  the 
distinctive  characters  of  the  following  components  of  hair  and 
follicle : 

f  Papilla  of  hair 

TT  •    J  Medullary  substance 

]  Cortical  substance 

[  Hair-cuticle  (outer  hair  membrane) 

(-  r  Cuticle  of  root  sheath 

Inner  root  sheath    <.  Huxley's  layer 

T-    -J  1    1      ^u  i  Henle's  layer 

Epidermal  sheath  ]  ^  ■' 


Hair-follicle  \  Outer  root  sheath   f  L^>''^'"  °!  hexagonal  cells 

I  ^  [  Layer  of  columnar  cells 

i 

I  f  Hyaline  layer  (glassy  membrane) 

I  Connective-tissue  sheath    \  Inner  fibrous  sheath 

[  [  Outer  fibrous  sheath 

Note  that  the  medullary  substance  is  not  so  well  differentiated  in  the  bulb 
as  in  the  lower  radix  of  the  hair  and  that  it  is  transformed  into  the  lumen  of  the 
scapus;  that  the  cortical  substance  consists  of  faintly  outlined  hexagonal  cells 
in  the  bulb,  elongated  cells  in  the  root,  and  flattened,  non-nucleated  scales  in 
the  scapus;  and  that  the  hair-cuticle  consists  of  a  layer  of  columnar  cells  in  the 
bulb  which  gradually  become  inclined  from  the  outside  downward  upon  the 
cortical  substance  so  that  they  overUe  each  other  on  the  root,  and,  on  the  scapus, 
having  lost  their  nuclei,  they  become  superficial,  imbricated  scales,  the  outlines 
of  which  may  be  observed  in  surface  \'iews  of  the  lower  part  of  the  scapus. 
Explain  the  differences  in  appearance  of  the  layers  of  the  hair-follicle  in  trans- 
verse sections  at  different  levels.  Compare  the  growth  of  the  hair  with  the 
formation  of  the  stratum  comeum  of  the  skin.  What  is  the  relation  of  the 
medullary  substance  to  the  layer  of  columnar  cells  of  the  outer  root  sheath  and 
to  the  connective  (mesodermal)  tissue  in  the  papilla  of  the  hair?  To  what 
structure  in  the  skin  does  the  hyaline  layer  correspond?  What  cells  bear  the 
pigment  of  the  hair?  Examine  the  longitudinal  sections  of  the  follicles  for  an 
arrector  pili  muscle.  Its  two  insertions  and  its  arrangement  with  reference  to 
the  angle  of  insertion  of  the  hair?  How  many  sebaceous  glands  to  each 
hair-foHicIe  ? 

2.  The  nails  (ungues). 

(a)  Macroscopic.     Examine  the  nails  of  the  hand  and  identify  free 
margin,  corpus,  lunula,  radix,  lateral  margin  and  vallum  of  the 


NERVE    TERMINATIONS    OF    THE    SKIN.  163 

nail.  What  is  the  relation  of  the  stratum  corneum  of  the  skin  to 
the  eponychium  and  hyponychium  ?  Explain  the  general  color  of 
the  nail  in  position  and  the  whitish  appearance  of  the  lunula. 

(b)  Pare  a  piece  of  nail  from  the  free  margin,  place  it  in  a  small  quantity 
of  20  per  cent,  potassium  hydrate  in  a  test  tube  and  boil  for  a  few 
minutes.  Then  place  it  in  a  drop  of  water  on  the  slide,  scrape  or 
tease  a  portion,  cover,  tap  the  cover-glass,  and  examine  the  frag- 
ments under  high  power.  What  has  been  the  action  of  the  alkali 
upon  the  nail?  Shape  and  arrangement  of  the  cells ?  Nucleated? 
Compare  with  stratum  corneum. 

(c)  From  a  longitudinal  stained  section  passing  vertically  through  a 
nail  and  involving  that  portion  of  the  extremity  of  a  finger  lying 
dorsal  to  the  third  phalanx,  make  a  drawing  under  low  power 
showing  the  parts  of  the  nail  and  its  structure,  position  and  intimate 
relation  to  the  epidermis  of  the  skin.  Note  that  the  corium  of  the 
skin  forms  the  "nail  bed"  which,  instead  of  sending  papillae  corii 
into  the  epidermis,  forms  ridges  parallel  to  the  long  axis  of  the  nail 
which  occupy  furrows  in  the  epidermis  with  cristfe  between.  Note 
further  that  the  radix  of  the  nail  extends  into  a  fold  or  duplication 
of  the  epidermis  and  thus,  here,  both  the  dorsal  and  concave  sur- 
faces are  closely  related  to  the  stratum  germinativUm.  Why  does 
the  radix  diminish  in  thickness  toward  its  termination?  On  the 
dorsal  surface,  what  is  the  relation  between  the  stratum  corneum, 
the  eponychium  and  the  nail  proper?  What  constitutes  the 
matrix  of  the  nail  and  what  is  its  extent  and  relation  to  the  lunula  ? 
Extent  of  the  stratum  granulosum?  Where  may  papillae  corii 
be  noted  ?  To  what  stratum  of  the  epidermis  does  the  nail  corres- 
pond? To  what  are  occasional  white  areas  in  the  body  due? 
Describe  the  process  of  growth  of  the  nail  explaining  the  greater 
width  of  its  free  end. 

D.  Blood-supply  of  the  Skin. 

I.  From  a  vertical  section  of  injected  skin,  make  a  drawing  illustrating 
the  abundance  and  arrangement  of  its  blood-supply,  merely  indicating 
the  boundaries  of  the  epidermis  in  outline.  How  is  the  stratum  germ- 
inativum  nourished?  In  what  layer  of  the  corium  are  the  vessels  largest? 
Of  the  general  blood-supply  of  the  body,  what  may  be  said  of  the  pro- 
portion devoted  to  the  skin  ? 

E.  Nerve  Terminations  of  the  Skin. 

I.  Nerves  oj  general  sensibility. 

(a)  From  a  gold  chlorid  or  methylen-blue  preparation  of  the  epidermis, 
draw  an  area  showing  the  so-called  ''/rcc  terminations''^  of  axons 
in   the  stratum  germinativum  either  upcni   the   "prickle  cells''  or 


164  LABORATORY    GUIDE    FOR   HISTOLOGY. 

among  the  cells  of  the  basal,  columnar  layer.  Note  the  repeated 
branching  of  the  sensory  fiber  prior  to  termination.  What  is  the 
relation  of  the  telodendria  to  the  protoplasm  of  the  cells  ?  Explain 
the  cessation  of  the  medullary  sheaths, 
(b)  From  a  similar  preparation  involving  longitudinal  sections  of  hair- 
follicles  (general  skin  of  white  rat  or  the  large  sensory  hairs,  vibrissas, 
of  the  cat)  study  and  illustrate  the  especially  rich  nerve-supply  of  the 
hair.  Number  of  axones  contributing  to  a  single  follicle?  Note 
that  the  axone  loses  its  medullary  sheath  upon  entering  the  outer 
root  sheath  of  the  hair  and  then  breaks  up  into  a  number  of  ter- 
minal twigs  which  encircle  the  epidermal  sheath  (plexus  of  Bonnet) 
below  the  sebaceous  gland.  Look  for  twigs  terminating  upon  the 
hyaline  layer  and  for  twigs  which  penetrate  this  to  terminate  upon 
the  epidermal  cells.  How  are  these  stimulated?  If  the  large 
sensory  hairs  are  studied,  note  the  peculiar  blood  sinus  of  the 
follicle.  Its  significance?  If  an  arrector  pili  muscle  is  present, 
look  for  pilo-motor  nerve  terminations. 

2.  Encapsulated  terminations  (corpuscle)  sub-epidermal. 

(a)  From  the  preparation  used  above  or  from  any  preparation  showing 
it,  draw  under  high  power  one  of  the  tactile  corpuscles  of  Meissner. 
Arrangement  of  the  capsular  tissue  and  the  behavior  of  the  termi- 
nating axone  within  it?  Where  does  the  medullary  sheath  cease? 
Position  of  the  corpuscle  as  suited  to  its  function  ? 

(b)  Make  an  illustration  of  a  lamellated  (Pacinian)  corpuscle  from 
one  taken  from  the  mesentery  of  the  cat  (methylen  blue  or  osmic 
acid).  Shape  and  size  of  the  corpuscle?  Of  what  tissue  are  the 
lamellae  formed?  Are  they  nucleated?  Their  relation  to  the 
neurilemma  of  the  axone?  Behavior  of  the  axone  in  terminating 
and  its  relation  to  the  nucleated  core  of  the  corpuscle?  As  found 
in  man,  what  is  the  position  of  this  variety  of  corpuscle  with  reference 
to  the  skin? 

Compare  the  corpuscles  studied  in  (a)  and  (b)  with  illustrations 
or  actual  preparations  of  corneal  corpuscles,  genital  corpuscles  of 
Krause,  and  also  with  the  corpuscles  of  Grandry  and  Herbst  found 
in  the  modified  skin  of  the  duck's  bill.  What  are  the  features  of 
similarity  existing  throughout  the  series  ? 

II.  THE  ORGAN  OF  TASTE. 

A.  Review  the  study  of  the  macroscopic  and  microscopic  features  of  the 
dorsum  of  the  tongue  made  when  considering  the  digestive  apparatus  (page  89). 
What  of  the  position,  appearance  and  relative  abundance  of  the  five  general 
varieties  of  lingual  papilhe?  From  personal  experience,  what  may  be  assumed 
as  to  the  abundance  of  the  general  sensory  inervation  of  the  lingual  epithelium  ? 


THE    OLFACTORY    ORGAN.  I 65 

Which  of  the  cranial  nerves  supply  these  afferent  axones?  What  areas  of  the 
tongue  and  pharynx  are  most  concerned  in  sensations  of  taste?  Consider, 
physiologically,  the  intimate  relations  between  gustatory  and  olfactory  sensa- 
tions. 

B.  From  an  ordinary  stained  section  passing  vertically  through  a  vallate 
(circumvallate)  papilla  of  the  human  (or  monkey)  tongue,  make  a  drawing 
under  low  power,  showing  the  whole  papilla  with  its  immediate  surroundings 
and  the  position,  shape  and  abundance  of  the  gustatory  calyculi  (taste-buds). 
These  structures  are  modifications  of  what?  What  in  the  lingual  papilla 
correspond  to  the  papillae  corii  of  the  skin  ? 

C.  Under  high  power,  draw  a  single  longitudinally  cut  calyculus,  showing 
the  shapes  and  interrelationships  of  the  varieties  of  cells  composing  it.  What  is 
the  relation  of  the  gustatory  pore  to  the  gustatory  filaments  and  their  relation 
to  the  neuro-epithelial  cells?     Significance  of  the  arrangement? 

D.  From  a  gold  chlorid  or  methylen-blue  preparation  of  taste-buds  (foliate 
papillcB  of  rabbit's  tongue)  m.ake  a  drawing  showing  a  taste-bud  in  outline  and 
the  entrance  and  form  of  termination  of  the  gustatory  axones.  Which  of  the 
varieties  of  the  epithelial  cells  is  especially  concerned  ? 

Are  taste-buds  the  only  portions  of  oral  epithelium  concerned  with  sensa- 
tions of  taste?  Discuss  the  adaptability  of  the  vallate  papilla  to  its  assumed 
function.  Which  of  the  encapsulated  nerve  terminations  does  the  taste-bud 
most  resemble?  To  which  cerebral  gyri  are  gustatory  impulses  chiefly  dis- 
tributed ?  Give  the  most  probable  pathway  and  the  number  of  neurones  inter- 
posed in  the  chain  by  which  the  impulses  reach  this  area. 

III.  THE  OLFACTORY  ORGAN. 

A.  Macroscopic. — Use  the  head  of  the  sheep  and  pig  fetus  from  which  the 
brain  has  been  removed,  either  fresh  or  that  used  and  preserved  in  formalin 
.when  the  preliminary  studies  of  the  central  nervous  system  were  made. 

1.  Note  the  two  olfactory  depressions  near  the  mid-line  in  the  anterior 
floor  of  the  cranium,  having  the  size  and  shape  of  the  ventral  surfaces 
of  the  olfactory  bulbs,  removed  from  them.  Remove  the  dura  mater 
and  examine  the  floor  of  these  depressions,  the  cribriform  laminae  of  the 
ethmoid  bone,  and  note  the  numerous  ethmoidal  foramina  through 
which  the  axones  of  the  olfactory  nerves  pass  to  enter  the  olfactory  bulbs. 
Variations  in  size  of  foramina?    Peculiarity  of  olfactory  axones? 

2.  Without  injuring  the  orbits,  remove  the  mid-portion  of  the  frontal 
bone  and  cut  away  the  nasal  bones  so  as  to  expose  the  nasal  cavity. 
What  differences  are  observable  between  the  respiratory  and  olfactory 
regions  of  the  nasal  epithelium?  Remove  a  small  piece  of  the  olfactory 
epithelium,  either  from  the  mesial  surface  of  the  superior  turbinated 


1 66  LABORATORY    GUIDE    FOR    HISTOLOGY. 

bone  or  from  the  perpendicular  plate  of  the  ethmoid,  place  in  0.5  per 
cent,  osmic  acid  four  to  twelve  hours  (if  material  has  been  preserved  in 
formalin,  wash  well  in  water  before  placing  in  osmic  acid),  and  then  place 
in  water  for  two  days  or  more  to  macerate.  What  is  the  approximate 
area  of  the  olfactory  region  in  man?  What  device  is  accomplished  by 
the  turbinated  bones  (conchse  nasales)  ?  What  is  the  vomero-nasal 
(Jacobson's)  organ? 

B.  Microscopic. 

1.  From  an  ordinary  stained  vertical  section  of  the  epithelium  of  the 
olfactory  region,  draw  a  narrow  strip  under  medium  magnification, 
showing  the  nature  of  the  epithelium  and  the  tela  submucosa.  How 
many  layers  of  nuclei  ?  Differences  of  epithelium  from  that  of  respira- 
tory region?  Where  is  the  pigment  situated  to  which  is  due,  in  the 
fresh,  the  difference  in  color  between  the  two  regions?  How  do  the 
nuclei  of  the  olfactory  cells  differ  from  those  of  the  sustentacular  cells? 
Explain  "olfactory  hairs."  Abundance,  nature  and  significance  of 
glands  of  Bowman? 

2.  Tease  on  the  slide  a  bit  of  the  epithelium  put  aside  in  A-2,  above, 
to  macerate,  mount  in  water  and  examine  ?  Sketch  some  of  the  isolated 
sustentacular  cells  and  one  or  two  olfactory  cells.  Varieties  of  the 
former  and  distinguishing  peculiarities  of  the  latter? 

3.  From  vertical  sections  of  olfactory  epithelium  (fetal  pig  or  new- 
born rat  or  rabbit),  stained  by  the  Golgi  method,  make  a  drawing, 
showing  the  shape  of  the  olfactory  cell,  its  relation  to  the  thickness  of 
the  mucous  membrane  and  the  origin  and  course  of  the  axone.  Does 
the  axone  branch? 

3.  From  Golgi  preparations  of  the  olfactory  bulb,  sectioned  vertical  to  its 
ventral  surface,  construct  a  drawing  showing  its  different  strata,  the 
varieties  of  its  cell-bodies  and  their  relation  to  the  olfactory  tracts. 
Significance  of  the  glomeruli  as  related  to  the  olfactory  cells  and  mitral 
cells?  What  gyri  comprise  the  cortical  area  of  smell?  Beginning 
with  the  olfactory  epithelium,  name  in  their  functional  order  the  different 
pathways  and  masses  of  gray  substance  com.prising  the  olfactory 
apparatus. 

The  studies  called  for  in  2  and  3  may  both  be  made  from  a  Golgi  section 
passing  vertically  through  the  upper  and  anterior  part  of  the  head  of  a 
fetal  rat  or  rabbit. 

IV.  THE  ORGAN  OF  HEARING. 
A.  External  ear. 

I.  With  the  aid  of  an  atlas  study  the  position  and  conformation  of  the 
living  auricle  (pinna)  with  reference  to  its  function.  Sketch  its  lateral 
aspect  naming  the  principal  parts.     In  the  ears  of  different  individuals. 


THE    MIDDLE    EAR.  .  1 67 

note  the  variations  in  the  lobule,  the  tragus,  antitragus  and  crus  of  the 
helix.  Occurrence  of  a  supratragal  tubercle  ?  Note  that  the  sulci  and 
fossae  are  roughly  continuous  with  each  other  and  into  the  external 
acoustic  meatus.  How  is  the  opening  (cartilaginous  portion)  of  the 
latter  guarded  against  foreign  particles?  What  is  the  position,  mor- 
phology, origin  and  function  of  the  ceruminous  glands?  Of  what 
variety  is  the  cartilage  of  the  auricle  and  that  of  the  external  meatus? 

2.   The  tympanic  membrane. 

(a)  From  descriptive  texts  or  atlas  determine  the  shape  and  environ- 
ment of  the  membrane  and  the  angle  at  which  it  is  placed  with 
reference  to  the  external  acoustic  meatus.  Carefully  dissect  the 
head  of  the  fetal  pig  (specimen  used  in  preliminary  study  of  the 
central  nervous  system)  so  as  to  expose  the  membrane.  Note  its 
variations  in  thickness,  its  tense  and  f3accid  regions,  its  border 
(limbus)  and  the  attachment  of  the  manubrium  of  the  malleus 
(umbo  and  malleolar  prominence).  What  predominating  arrange- 
ment of  the  fibrous  structure  of  the  membrane  is  evident  ?     Remove 

■a  portion,  mount  in  water  and  examine  under  low  power.     What 
is  the  difference  of  the  two  sides? 

(b)  From  a  vertical  stained  section  of  the  tympanic  membrane  taken 
away  from  the  attachment  of  the  manubrium,  make  a  drawing 
under  high  power  illustrating  its  three  layers:  (i)  The  cutaneous 
layer,  continuous  with  the  stratified  squamous  epithelium  lining 
the  external  meatus  and  with  no  papillae  corii.  How  many  layers 
of  cells?  Nature  of  stratum  corneum?  (2)  The  fibrous  layer 
(lamina  propria)  consisting  of  an  inner  circular  stratum  of  connec- 
tive tissue  fibers  and  an  outer  stratum  radiating  from  the  attach- 
ment of  the  manubrium  of  the  malleus.  Blood-vessels?  (3)  The 
mucous  layer  consisting  of  a  layer  of  simple  epithelium  resting  upon 
a  basement  membrane  which  is  intimately  connected  with  the 
circular  fibrous  stratum.  From  which  germ  layer  is  this  epithelium 
derived  ? 

The  Middle  Ear  {tympanum,  tympanic  cavity). 

I.  Become  familiar  with  the  position  and  size  of  the  cavity  and  with 
the  parts  and  relationship  of  the  three  auditory  ossicles.  Is  the  arrange- 
ment of  the  ossicles  such  that  the  vibrations  of  the  tympanic  membrane 
are  magnified  as  transmitted  to  the  membrane  closing  the  fenestra 
tympani?  Attachments  and  action  of  the  tensor  tympani  muscle? 
Origin,  function  and  course  of  the  chorda  tympani?  Nature  of  the 
lining  of  the  tympanic  cavity  and  its  variation  in  the  region  of  the 
opening  of  the  Eustachian  or  auditory  tube?  What  is  the  structure  of 
the  wall  of  this  tube  and  for  what  purpose  and  with  what  does  it 
connect  the  tympanic  cavity? 


1 68  LABORATORY    GUIDE    FOR   HISTOLOGY. 

2.  Remove  the  osseous  labyrinth  from  the  head  of  the  fetal  pig  used 
above.  (In  pig  fetuses  at  term  or  shortly  after  birth,  the  labyrinths  have 
not  become  fused  to  the  surrounding  petrosal  portion  of  the  temporal 
bone  and  may  be  "shelled  out"  without  difficulty.)  Insert  a  needle 
between  the  crura  of  the  stapes  and  remove  it  from  its  position  over  the 
fenestra  vestibuli  (ovalis).  Return  the  labyrinth  to  formalin  solution 
and  place  the  stapes  in  a  watch  glass  of  water  (or  dehydrate,  clear,  and 
mount  in  a  cell  slide)  and  draw  under  low  power  showing  capitulum, 
anterior  and  posterior  cms,  basis,  and  obturator  membrane  of  stapes. 
Is  this  membrane  perforated  naturally?  Shape  and  peculiarity  of  basis 
of  stapes?     Attachment  and  action  of  stapedius  muscle? 

C.  The  Inner  Ear  (the  labyrinth). 

1.  Place  the  osseous  labyrinth  (removed  above)  in  a  watch  glass  with 
water  enough  to  cover  it,  and,  under  dissecting  microscope,  make 
outline  drawings  of  both  the  mesial  or  posterior  and  the  lateral  or  anterior 
aspects,  showing  and  naming  the  three  semicircular  canals  with  their 
ampullae,  the  vestibule  with  fenestra  vestibuli  and  fenestra  cochleae, 
and  cochlea  with  its  cupola  and  base.  It  is  desirable  to  dissect  away 
some  of  the  bone  to  better  expose  the  semicircular  canals  and  vestibule. 
Note  the  acoustic  nerve  divided  into  its  vestibular  and  cochlear  branches. 
By  reference  to  texts  and  illustrations  determine  the  position  and  signif- 
icance of  the  sacculus,  utriculus,  endolymphatic  duct,  the  communi- 
cations of  the  semicircular  canals  with  the  vestibule,  and  the  three 
maculae  cribrosae  (perforated  spots).  Return  the  osseus  labyrinth  to  the 
formalin  solution. 

2.  The  membranous  labyrinth. 

(a)  From  a  stained  section  of  the  entire  labyrinth  involving  a  vertical 
axial  section  of  the  cochlea  (fixed  for  three  days  in  Zenker's  fluid 
or  for  twenty-four  hours  in  Perenyi's  fluid,  either  of  which  fluids 
decalcifies  while  fixing),  draw  under  low  power  showing  the  inter- 
relations and  naming  the  following  structures  of  the  cochlea: 

The  cochlear  nerve,  spiral  ganglion,  osseous  spiral  lamina,  basilar 
lamina  (lamina  spiralis  membranacea),  basilar  crest,  spiral  liga- 
ment, spiral  prominence,  spiral  organ  (organ  of  Corti),  spiral  limbus, 
spiral  sulcus,  vestibular  lip  (with  Buschke's  teeth),  tectorial 
(Corti's)  membrane,  vestibular  (Reissner's)  membrane,  scala 
vestibuli,  duct  of  cochlea,  scala  tympani,  and  spiral  canal  (tunnel 
of  Corti).  What  is  the  modiolus?  Look  for  hamulus  of  spiral 
lamina.  What  is  the  heHcotrema?  Its  functional  significance? 
Derivation  and  general  course  of  the  blood-supply  of  the  cochlea  ? 

(b)  Make  a  drawing  under  high  power  including  the  spiral  limbus 
and    sulcus,    the    tectorial    membrane,   the    basilar  lamina,    and 


THE    MEMBRANOUS    LABYRINTH,  169 

showing  in  detail  the  spiral  organ  (organ  of  Corti).     \\Tiat  is  the 
tympanic  lip  ?     What  is  the  difference  between  the  cells  of  Claudius, 
cells  of  Hensen,  and  Deiters'  cells?     Nature,  functional  significance 
and  difference  in  number  of  outer  and  inner  hair-cells  ?    What  is  the 
linear  arrangement  of  the  pillars  (rods)  of  Corti  ?     Of  the  pairs  of  pil- 
lars, which  is  the  longer  and  more  slender  and  where  are  their  nuclei 
situated?     What  is  the  origin,  structure  and  functional  significance 
of  the  tectorial  membrane  ?     From  its  variations  as  seen  in  sections 
in  the  different  turns  of  the  cochlea,  what  can  be  said  of  the  shape  of 
this  membrane?     Note  that  the  basilar  lamina  consists  of  a  tym- 
panic, cellular  lamina  which  contains  the  tortuous  vas  spirale,  and 
of  an  upper,  dense  connective  tissue  lamina,  the  basilar  membrane. 
What  theoretical  significance  has  been  attached  to  the  latter  and 
what  facts  of  structure  are  urged  against  the  theory?     What  is  the 
structure  of  Reissner's  membrane?     What  variety  of  nerve  cell- 
body  comprises  the  spiral  ganglion?     How  do  the  terminal  twigs 
of  the  peripheral  axones  of  these  reach  the  outer  hair-cells  ? 
(c)  Gently  crush  the  osseous  labyrinth,  studied  above,  place  in  watch 
glass  of  water  vmder  the  dissecting  microscope  and,  with  teasing 
needles  and  fine-pointed  forceps,  carefully  remove  the  bits  of  bone 
so  as  to  expose  the  membranous  labyrinth.     Work  over  a  black 
surface.     How  many  turns  in  the  cochlea  of  the  pig?     Transfer  to 
clean  water  and  carefully  remove  (tear  off  with  the  forceps)  the 
outer  portion  of  the  wall  of  the  scala  vestibuH  and  identify  cupular 
cecum,  helicotremma,  Reissner's  membrane,  the  tectorial  membrane 
(veiy  fragile),  the  vestibular  lip  of  the  spiral  lamina,  and  the  basilar 
membrane.     Remove  bits  of  the  spiral  structures  upon  a  slide  and  ex- 
amine with  compound  microscope,  using  low  light.    Note  "  Huschke's 
teeth  "as  seen  on  the  flat;  the  structure  of  the  basilar  membrane  and 
the  course  of  the  vas  spinale  below  it;  the  ease  with  which  Reissner's 
membrane  is  removed  and  the  course  of  the  blood-vessels  within 
it;  and  the  fact  that  the  tectorial  membrane  easily  floats  free  from 
its  attachment  when  disturbed.     If  possible,  mount  a  portion  of 
this   membrane,  basal   surface   upward,  and   examine  under  high 
power.     Its  fibrous  structure,  supported  in  a  xqtj  flexible  glutinous 
substance,  may  be  observed  and   the  peculiar  arrangement  of  the 
fibres  producing  the  appearance  of  its  three  zones,  and  Hensen's 
line,  which  lies  over  the  interlocking  phalanges  of  the  pillars  of  Corti, 
may  be  identified.     What  is  the  relation  of  the   ascending  scala 
vestibuli  to  the  descending  scala  tympani  with  reference  to  wave 
motion  transferred  to  the  fluid  in  them  ? 
(d)  Name  the  four  branches  of  the  vestibular  division  of  the  acoustic 
nerve  and  the  locahties  of  their  termination.     Where  are  the  cells 
of  origin  of  the  saccular  (a  branch  of  the  cochlear  nerve)  and  of  the 


170  LABORATORY    GUIDE    FOR   HISTOLOGY. 

posterior  ampullar  nerves?  To  what  in  the  cochlea  do  the  hairs 
of  the  macula;  accustic^e  of  the  utriculus  and  sacculus,  and  those  of 
the  cristcc  of  the  ampulla;  correspond  ?  The  otolith  membranes  and 
the  cupulse?  Significance  of  otoliths?  In  the  preparation  used 
in  (a)  and  (b)  above,  identify  sections  of  the  semicircular  canals 
and  of  the  sacculus  or  utriculus.  In  a  section  of  a  semicircular 
canal,  away  from  the  ampulla,  note  the  relatively  small  endolymph 
canal  (semicircular  duct)  and  the  much  larger  perilymph-space 
separated  by  connective  tissue  partitions  (ligaments),  all  the  spaces 
being  lined  by  a  simple,  flat  epithelium.  Difference  of  origin  of  the 
epithelium  of  the  endolymph  canal?  Name  and  position  of  the 
duct  by  which  the  original  continuity  of  the  entire  membranous 
labyrinth  is  retained  ? 

Sketch  a  section  of  a  semicircular  canal,  naming  locality  and  parts 
represented. 
3.  WOiat  cerebral  gyri  and  what  portions  of  them  comprise  the  cortical 
area  of  hearing?  With  what  divisions  of  the  encephalon  are  the  central 
connections  of  the  vestibular  nerve  peculiarly  concerned?  Review 
the  location  and  connections  of  the  nuclei  of  termination  of  the 
acoustic  nerve  and,  beginning  with  the  organ  of  Corti  and  the  maculee 
and  cristae  acousticEe,  construct  a  diagram  illustrating  the  variety, 
course  and  connections  of  the  neurones  of  the  acoustic  apparatus. 

V.  THE  ORGAN  OF  VISION. 

A.  Macroscopic. 

1.  With  the  aid  of  a  mirror,  sketch  the  eye  in  position,  showing  the 
supercilium  (eyebrow)  with  the  varying  directions  of  the  hairs  composing 
it;  the  superior  and  inferior  palpebrae  with  their  cilia  (eyelashes), 
their  commissures  and  anterior  and  posterior  limbs;  the  medial  and 
lateral  anguli  oculi;  the  coruncula  and  papilla  lacrymalis  (opening  of 
duct  of  lacrymal  gland) ;  the  cornea  with  the  iris  and  pupil  showing 
through  it,  and  the  sclera.  Note  the  annuli  and  zones  of  the  iris.  Allow 
changes  in  the  intensity  of  the  light  entering  the  eye  and  note  changes 
in  the  diameter  of  the  pupil  produced  by  the  accomodative  activity  of 
the  ciliary  muscles.  Retract  the  inferior  palpebra  and  observe  that  the 
conjunctiva  bulbi  is  continuous  with  the  conjunctiva  palpebrarum. 
Note  the  superficial  blood-supply  of  the  bulb. 

2.  Carefully  dissect  out  the  bulbus  oculi  of  the  sheep  (from  the  head 
preserved  in  formalin  when  making  the  preliminary  study  of  the  brain), 
retaining  a  portion  of  the  optic  nerve  and  the  eye-moving  muscles 
attached  to  the  bulb.  Determine  the  shape,  relative  size  and  locality 
of  attachment  of  the  six  extrinsic  muscles  and  give  the  name,  function 
and  innervation  of  each.    Note  the  occurrence  and  peculiarity  of  arrange- 


«     THE    RETINA.  I7I 

ment  of  the  M.  retractor  bulbi  possessed  by  the  sheep.  What  distin- 
guishes the  superior  oblique  muscle  ?  Size,  position  and  appearance  of 
the  lacrymal  gland  ?  Dissect  so  as  to  determine  the  relation  of  the  cranial 
dura  and  pia  mater  to  the  optic  nerve. 

3.  With  razor  bisect  the  bulb  in  the  horizontal  meridian  of  the  optic 
nerv'e.     Place  in  water  and  identify  the  following: 

(a)  Anterior  camera  oculi  (anterior  chamber)  containing  the  aqueous 
body  (humor). 

(b)  The  cystalline  lens. — Note  its  position  and  the  difference  in  cur\'ature 
of  its  anterior  and  posterior  surfaces.  Action  of  the  formalin  upon 
it? 

(c)  The  posterior  chamber  containing  the  vitreous  body  (humor). 
Difference  between  this  and  aqueous  body?  Note  course  of 
hyaloid  canal  and  hyaloid  artery.     \Miere  is  the  posterior  camera? 

(d)  The  three  tunics  oj  the  eye. 

(i)  The  fibrous  or  external  tunic  forming  the  sclera  and  the  cornea. 
Dift'erence  in  appearance  of  the  two  parts  and  the  action  of  for- 
malin upon  the  latter?  Determine  the  existence  of  the  anterior 
corneal  epithelium  (conjunctivum).  Tease  a  bit  of  the  cornea 
and  e.xamine,  mounted  in  water,  for  the  direction  of  its  structural 
arrangement  and  the  presence  of  nuclei. 

(2)  The  vascular  or  middle  tunic  comprising  the  chorioidea,  the 
ciliary  body  and  the  iris.  Of  the  chorioidea,  note  the  lamina 
vasculosa,  containing  numerous  blood-vessels  covered  with  pig- 
ment, and  the  thin  lamina  basilaris.  Of  the  ciliar}^  body,  dis- 
tinguish the  ciliary  folds  and  processes  (corona  ciliaris),  the 
orbiculus  ciliaris,  and  the  ciliary  zone  (zone  of  Zinn)  consisting 
of  zonular  fibres  attaching  the  ciliar}-  body  to  the  capsule  of  the 
crystalline  lens  (suspensor}^  ligament).  Of  the  iris,  a  continu- 
ation of  the  chorioidea  and  ciliary  body,  note  the  stroma  of  the 
iris,  consisting  of  abundant  connective  tissue  and  radially  arranged 
blood-vessels,  and  the  posterior  pigment  layer  of  the  iris. 

(3)  The  retina  or  internal  tunic,  the  thinnest  of  the  tunics  and  dis- 
tinguished from  the  middle  one  by  its  whiteness.  It  lies  loosely 
except  for  its  attachment  to  the  ciliarv'  body  and  its  continuation 
into  the  optic  nerve,  and  consists  of  three  portions.  Distinguish 
its  optic  portion  and  its  ciliary  portion  (pars  ciliaris  retinte),  the 
boundary  between  the  two  portions  appearing  as  a  zig-zag  line, 
the  ora  serrata.  The  cilian,-  portion  extends  from  the  ora 
serrata  to  the  outer  border  of  the  iris.  The  third  or  iridic  por- 
tion of  the  retina  underlies  the  iris,  extending  from  its  outer  or 
ciliar}'  border  to  its  pupillary  border  and,  therefore,  forms  the 
posterior  or  pigment  layer  of  the  iris  mentioned  above.  Remove 
a  bit  of  the  posterior  portion  of  the  pigment  layer  of  the  retina. 


172  LABORATORY   GUIDE    FOR   HISTOLOGY. 

continuous  with  the  ciliary  and  iridic  portions,  mount  it  in  water 

and  examine,  distinguishing  it  from  the  adherent  pigment  cells  of 

the  chorioidea.     Peculiarities?     Note  the  papilla  of   the  optic 

nerve  with  its  central  depression  (excavation). 

From  which  of  the  germ  layers  are  each  of  the  three  tunics  of  the 

eye  derived?     From  its  development,  to  what  does  the  retina 

correspond?     To  which  encephalic  meninges  do  the  sclera  and 

chorioidea  correspond?      Origin  and  localities  of 'entrance  of  the 

blood-vessels  of  the  eye-bulb  ?     Examine  the  optic  nerve  for  the 

central  vessels  of  the  retina. 

(e)  With  dissecting    microscope    examine  the  crystalline  lens  under 

water  over  a  black  surface.     What  is  the  apparent  arrangement 

of  its  structure?     Tease  the  lens,  identifying  its  capsule,  cortical 

substance  and  nucleus.     What  is  the  shape  of  the  lens-fibres  and 

how  do  they  run?     Nature  of  cement  substance?     Why  does  the 

lens  tend  to  break  up  into  concentric  lammellee?     Origin  of  the 

lens? 

B.  Microscopic. 

1.  Under  low  power,  draw  a  stained  horizontal  section  of  an  entire 
bulbus  oculi  (human,  monkey  or  dog,  fixed  in  Perenyi's  fluid  for  soften- 
ing the  lens  and  embedded  in  celloidin).  Show  the  arrangement  of  and 
name  the  structures  identified  above.  In  addition,  show  that  the 
muscles  of  the  ciliary  body  and  iris  are,  in  each,  arranged  into  a  radial 
(meridianal)  system  and  a  circular  system.  Explain  the  function  of  the 
fibres  belonging  to  each  system.  Origin  of  the  motor  axones  supplying 
the  ciliary  muscles  and  the  radial  and  sphincter  pupillae  of  the  iris? 
Note  the  cessation  of  the  optic  portion  of  the  retina  at  the  ora  serrata, 
and  explain  the  function  of  the  zonalar  fibres  (ciliary  zonule)  which  pass 
from  the  ciHary  body  and  are  attached  upon  the  capsule  of  the  crystalline 
lens.  Indicate  the  epithelium  of  the  lens,  the  arrangement  of  the  lens- 
fibres  and  the  locality  in  which  the  fibres  possess  nuclei.  Nature  of  the 
lens  capsule  ?  Is  there  both  an  anterior  and  a  posterior  corneal  epithe- 
lium? Identify  other  laminae  of  the  cornea,  the  venous  sinus  of  the 
sclera  (the  canal  of  Schlemm),  and  the  ciliary  blood-vessels.  What  is 
the  difference  between  the  cells  of  the  chorioidea  and  those  of  the 
pigment  layer  of  the  retina?  Look  for  the  lamina  chorio-capillaris  and 
the  lamina  basilis  of  the  chorioidea.  What  is  the  difference  between 
the  optic  axis  of  the  bulb  and  the  visual  axis?  Where  is  the  macula 
lutea  (yellow  spot)  with  its  fovea  centralis,  and  from  its  situation  what 
may  be  inferred  concerning  it? 

2.  From  a  stained,  thin,  vertical  section  of  the  optic  portion  of  the  retina 
(human  or  dog,  removed  separately  and  sectioned  in  paraffin),  make  a 
careful  drawing  under  high  power  of  a  small  segment  showing  and 


LAYERS    OF    THE    RETINA.  1 73 

naming,  from  the  outer  inward,  in  their  order  and  relationship,  the 
eleven  strata  into  which  the  three  actual  layers  of  functional  elements 
are  divided,  as  follows: 
(a)  Pigment  layer  of  the  retina  (pigmented  epithelium). 

■  (i)  Layer  of  rods  and  cones. 

(2)  External  limiting  membrane. 

(3)  Outer  nuclear  layer. 

(4)  Henle's  fibre  layer. 
(i)   Outer  reticular  (molecular)  layer. 

(2)  Outer  ganglionic  (inner  nuclear)  layer. 

(3)  Inner  reticular  (molecular)  layer. 

(4)  Inner  ganglionic  (ganglion  cell)  layer. 

(5)  Nerve-fibre  (optic  nerve)  layer. 

(6)  Internal  limiting  membrane. 


(b)  The  neuro-epithelial  layer 
{radio-sensitive  or  visual  cells) 


(c)  Ganglionic  layer 
{cerebral  layer) 


What  are  the  rods  and  cones  cytologically  ?  Number  and  appearance 
of  the  segments  into  which  they  may  be  divided?  Arrangement  of  the  nuclei 
to  which  they  belong?  Numerical  relation  of  rods  to  cones?  What  is  the 
external  limiting  membrane?  What  is  the  source  of  rhodopsin  or  "visual 
purple"  and  upon  which  elements  does  it  act?  Changes  in  nerve-fibre  layer  in 
passing  from  ora  serrata  to  papilla  of  optic  nerve  (see  section  used  above),  and 
its  relation  to  inner  ganglionic  layer  and  to  optic  nerve?  What  constitutes 
the  internal  limiting  membrane?  What  differences  are  to  be  noted  in  the 
nuclei  of  the  different  layers?  Compare  the  drawing  with  a  section  passing 
through  the  fovea  centralis  (demonstration  preparation  if  section  used  does 
not  involve  fovea).  Note  the  changes  in  the  different  strata  producing  the  fovea 
centralis  and  explain  the  reason  for  the  name  "  macula  lutea."  Significance 
of  the  peculiar  character  of  the  neuro-epithelial  layer  in  region  of  fovea? 
Behavior  of  the  nerve-fibre  layer  in  the  region  of  the  fovea  ? 

3.  With  the  aid  of  Golgi  preparations  of  the  retina  and  descriptive 
texts,  construct  a  drawing  showing  the  significance  and  intimate  relation- 
ship of  the  retinal  elements  composing  the  layers  designated  above. 
Include  one  or  two  of  the  radial  masses  of  the  supporting  tissue  (fibres 
of  Mliller)  of  the  retina,  showing  their  peculiarities  of  form,  the  retinal 
layers  through  which  they  extend,  the  layer  to  which  their  nuclei  belong, 
and  their  relation  to  the  external  and  internal  limiting  membranes. 
What  comprises  the  outer  and  inner  reticular  layers?  Compare  the 
"bipolar  cells"  (nuclei  of  which  form  outer  ganglionic  or  inner  nuclear 
layer)  with  the  neurones  of  a  spinal  ganglion,  and  give  reasons  for  their 
being  called  the  "ganglion  retince."  Indicate  the  position,  shape  and 
functional  significance  of  two  or  three  varieties  each  of  amacrine  cells 
and  horizontal  cells.  Why  are  they  so-called  ?  To  what  cells  in  nerve  gan- 
glia and  in  the  cerebral  and  cerebellar  cortex  do  they  correspond  ?  Exam- 
ine the  drawing  made  in  2,  above,  for  nuclei  probably  belonging  to  amacrine 


174  LABORATORY    GUIDE    FOR   HISTOLOGY. 

cells  and  so  label  them.  Also  include  in  the  present  drawing  a  centrifugal 
axone  (entering  the  retina  from  the  direction  of  the  central  nervous 
system),  showing  its  course  and  the  retinal  layer  in  which  it  terminates. 
Give  physiological  evidence  for  the  existence  of  such  axones. 
4.  Construct  a  diagram  illustrating  the  varieties  and  arrangement  of  the 
retinal  cells  and  the  neurones,  cerebral  and  retinal,  interposed  in  the 
visual  apparatus,  naming  the  different  portions  of  the  pathways  and  the 
nuclei  involved,  and  indicating  the  cerebral  gyri  comprising  the  cortical 
area  of  vision.  In  what  animals  in  general  is  there  a  total  decussation 
of  optic  fibres  in  the  chiasma  ?  Which  fibres  decussate  in  man  ?  What 
axones  form  the  inferior  cerebral  (Gudden's)  commissure?  How  are 
eye  movements  associated  with  visual  impulses  ? 

LITERATURE  ON  THE  SENSE  ORGANS. 
Skin. — Tactile  Apparatus. 

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Corresp. -Bl.  d.  deutschen  Gesells.  f.  Anthropol.  Ethnoi.  u.  L^rgesch.,  Jg.  35,  No.  3, 

p.  18,  1904 
DIEM,  F.     Beitrage  zur  Entwicklung  der  Schweissdrusen  an  der  behaarten  Haut  der  Sauge- 

thiere.     Anat.  Hefte,  Abt.  i,  H.  102  (Bd.  34,  H.  i),  p.  187,  1907. 
DOGIEL,  A.  S.     Die  Nervenendigungen  im  Nagelbett  des  Menschen.     Arch.  f.  Mik.  Anat., 

Bd.  64,  H.  I,  1904. 
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the  Volar  Surface  of  the  Hand.     Jour,  of  Anat.  and  Physiol.,  Vol.  41,  Pt.  i,  p.  66, 

1906. 
FREDERIC,  J.     Nachtrag  zu  den  Untersuchungen  iiber  die  Sinushaare  der  Affen.     Zeit.  f. 

Morphol.  u.  Anthropol.,  Bd.  9,  H.  3,  p.  327,  1906. 
HERRICK,  C.  L.,  and  COGHILL,  G.  E.     The  Somatic  Equilibrium  and  the  Nerve  Endings 

in  the  Skin.     Jour,  of  Comp.  Neurol.  Vol.  8,  No.  i,  1898. 
HUBER,  G.  C.,  and  ADAMSOM,  E.  W.  A  Contribution  on  the  Morphology  of   Sudoripar- 
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1903. 
INGBERT,  C.  E.     On  the  Density  of  the  Cutaneous  Innervation  in  Man.     Jour,  of  Comp. 

Neurol.,  Vol.  13,  No.  3,  1903. 
KIDD,  \V.     The  Papillary  Ridges  and  Papillary  Layer  of  the  Corium  in  the  Mammahan 

Hand  and  Foot.     Jour,  of  Anat.  and  Physiol.,  Vol.  41,  Pt.  i,  p.  35,  1906. 
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SMITH,  G.  E.,  The  Morphology  of  the  Occipital  Region  of  the  Cerebral  Hemisphere  in 
Man  and  the  Apes.     Anat.  Anz.,  Bd.  24,  No.  16-17,  p.  436,  1904. 

USHER,  C.  H.,  and  DEAN,  G.  Experimental  Research  on  the  Course  of  the  Optic  Fibres. 
Brain,  Pt.  104,  p.  524,  1904. 

VERMES,  L.  Ueber  die  Neurofibrillen  der  Retina.  Anat.  Anz.,  Bd.  26,  No.  22-23,  p. 
601,  1905. 

ZUERN,  J.  Vergleichend-histologische  Untersuchungen  iiber  die  Retina  und  die  Area  Cen- 
tralis retinae  der  Haussaugetiere.  Arch.  f.  Anat.  und  Ent wick.  Jg.  1902.  Suppl. 
Bd.,  p.  99, 


SECTION  III. 

THE  METHODS  OF  PREPARATION  EMPLOYED. 

To  accomplish  the  anatomical  studies  suggested  in  Section  II,  the  student 
will  not  have  time  to  apply  the  methods  involved  in  the  preparation  of  his 
material  other  than  those  few  for  which  directions  are  given  in  that  section. 
It  is  considered  neither  advisable  nor  wise  that  he  should  spend  time,  which 
should  be  devoted  to  the  real  subjects  of  the  course,  upon  the  routine  methods 
of  making  sections  and  staining.  A  far  more  economic  arrangement  is  that  the 
sections  be  prepared  for  the  whole  class  by  one  man  especially  experienced  in 
this  work,  and  such  an  arrangement  is  expected  here.  Some  familiarity  with 
the  general  processes  of  fixing,  embedding,  sectioning  and  staining  is  assumed 
to  have  been  attained  by  the  student  in  his  high  school  work  and  in  courses 
taken  prerequisite  to  this.  Such  familiarity  will  enable  him  to  follow  the  easily 
available  directions  for  any  of  the  special  and  more  complicated  methods 
should  occasion  arise  later  for  him  to  employ  them. 

Detailed  descriptions  of  the  various  methods  employed  in  making  the 
preparations  suggested  in  this  Laboratory  Guide  are  not  deemed  necessary  from 
the  fact  that  they  are  given  in  all  the  descriptive  texts  of  histology,  some  one  of 
which  must  be  used  in  conjunction  with  this  guide.  For  a  greater  variety  of 
methods,  and  modifications  of  the  methods  used  here,  the  student  must,  at 
need,  consult  the  reference  works  devoted  to  microscopical  technic,  such  as 
Lee's  Microtomists'  Vade-Mecum,  Guyer's  Animal  Micrology,  Hardesty's 
Neurological  Technic,  or,  for  example,  the  numbers  of  the  Zestschrift  fiir 
wissenschaftliche  Mikroscopie  and  the  Zentralblatt  fiir  Normale  Anatomic  und 
Microtechnik.  It  may  at  times  be  necessary  to  refer  to  the  original  paper  of 
the  author  who  has  devised  a  method  or  a  modification  of  a  method  for  obtain- 
ing special  results. 

In  order  that  the  student,  and  the  assistant  who  prepares  the  material  for 
the  course  of  study  outlined,  may  more  easily  see  what  methods  are  called  for, 
they  are  enumerated  below.  All  of  the  fluids  are  in  common  use  and  their 
formula;  may  be  found  in  the  reference  books  or  in  the  papers  cited. 

I.  The  general  method,  that  by  which  most  of  the  sections  are  prepared, 
consists  in  fixing  the  tissue  in  Gilson's  or,  preferably,  Zenker's  fluid,  washing 
as  required;  embedding  in  celloidin,  staining  the  sections  with  Delafield's 
hematoxylin^  decolorizing  with  acid  alcohol,  couterstaining  with  o.i  per  cent. 
Congo  red,  dehydrating  with  graded  alcohols,  distributing  the  sections  in  the 
students'  section  dishes,  which  contain  creasote  or  any  good  clearing  mixture 
for  celloidin  sections,  where  they  are  cleared  and  from  which  they  are  placed  on 
the  slides  by  the  students,  the  surplus  clearing  fluid  blotted  up  with  filter  paper 

179 


l8o  LABORATORY    GUIDE    FOR    HISTOLOGY. 

and  the  sections  mounted  in  balsam.  Congo  red  as  a  counterstain  is  preferable 
to  the  commonly  used  eosin  because  it  brings  out  cell  boundaries  and  delicate 
reticula  better,  and  also  differentially  stains  certain  gland  ducts,  gastric  cells,  etc. 

2.  Van  Giisen's  Method. — Celloidin  sections  are  prepared  as  above,  stained 
with  Delafield's  hematoxylin,  and  simultaneously  decolorized  and  counter- 
stained  with  Van  Giesen's  picric-acid-fuchsin  mixture,  washed  and  dehydrated 
in  alcohol,  and  distributed  to  the  students  as  above. 

3.  For  cell  division. — (a)  Vegetable  tissue  is  fixed  in  Flemming's  fluid, 
washed  as  required  after  that  fluid,  embedded  in  paraffin,  sectioned  thin,  sections 
fixed  on  slide,  paraffin  removed  with  xylol,  sections  carried  through  graded 
alcohols,  to  50  per  cent,  alcohol,  and  stained  12  to  24  hours  in  a  mixture  of  equal 
parts  saturated  alcoholic  solution  of  safranin  and  anilin  water.  Sections  are 
then  decolorized  in  anilin  alcohol,  rinsed  in  50  per  cent,  alcohol,  stained  2  to  4 
hours  in  a  saturated  aqueous  solution  of  gentian  violet,  rinsed  in  anilin  alcohol, 
dehydrated  (a  few  seconds)  in  absolute  alcohol,  differentiated  with  clove  oil, 
dipped  through  xylol,  and  mounted  in  balsam.  The  necessary  times  for 
decolorization  and  differentiation  must  be  determined  by  examination  under 
the  microscope. 

(b)  Animal  tissue  is  fixed  in  either  saturated  corrosive  sublimate  and 
washed  as  required,  or  fixed  in  Van  Gehuchten's  (Carnoy's)  fluid,  embedded 
in  paraffin,  sectioned  thin,  sections  fixed  on  slide,  paraffin  removed,  sections 
treated  with  alcohols,  stained  by  Heidenhein's  Iron-hematoxylin  method, 
counterstained  with  orange  G.  or  weak  f  uchsin,  washed,  dehydrated,  cleared  in 
xylol  and  mounted  in  bilsam.  They  may  be  stained  with  Delafield's  hema- 
toxylin and  lightly  counterstained  with  congo  red  or  eosin. 

4.  Digestion  for  Reticular  Tissue. — Small  blocks  of  fresh  spleen  or  lymph- 
gland  may  be  fixed  in  96  per  cent,  alcohol,  Van  Gehuchten's  fluid  or  Zenker's 
fluid,  washed  w.ell  with  water  and  subjected  to  the  action  of  pancreatin  dis- 
solved in  weak  sodium  bicarbonate,  in  a  thermostat  as  described  by  Flint 
(Johns  Hopkins  Hosp.  Bull.,  vol.  13,  1902).  Afterward  the  block  of  tissue 
is  carefully  washed,  embedded  in  paraffin,  and  sections  stained  with  acid  fuchsin 
or  anilin  blue.  Or,  thin  free  hand  sections  of  the  fixed  blocks  may  be  digested 
in  the  pancreatin  solution,  washed,  stained,  dehydrated,  cleared,  and  mounted. 
The  latter  is  the  more  rapid  method  but  is  too  coarse  for  delicate  frameworks. 

5.  Injections. — For  the  finer  blood-supply  of  tissue  and  organs,  a  good 
carmin-gelatin  injection  mass  is  preferable.  It  is  employed  in  the  usual  way 
with  animals  which  have  been  chloroformed  long  enough  for  relaxation  of  the 
tissues  to  take  place,  the  injection  long  continued  under  low  pressure,  the 
whole  hardened  and  cooled  in  alcohol  for  several  hours  and  then  the  parts 
desired  removed  and  further  hardened  and  preserved  in  alcohol.  The  pre- 
cautions followed  by  Walker  in  making  the  injection  mass  will  give  excellent 
results  (Am.  Jour.  Anat.,  vol.  5,  No.  i,  p.  73,  1905).  For  the  lymphatics,  an 
injection  mass,  more  fluid  than  the  gelatin  mass,  is  necessary.  An  aqueous 
solution  of  Berlin  blue  is  often  used.     Instead  the  haphazard,  commonly  used. 


THE    GOLGI    METHOD.  181 

puncture  method  of  injecting  lymphatics,  in  most  cases  it  will  be  found  more 
expedient  to  use  the  "needle  and  clamp  device"  described  by  Prof.  W.  S. 
Miller  (Johns  Hopkins  Hosp.  Bull.,  vol.  i6,  No.  173,  1905). 

6.  The  Golgi  method  is  employed  for  three  purposes:  (i)  For  the  demon- 
stration of  neuroglia  and  of  the  nervous  elements  in  both  their  central  and 
peripheral  relations;  (2)  For  certain  of  the  ducts  of  the  gastric  glands,  and  (3) 
for  the  bile  capillaries.  For  fresh  tissue,  "the  rapid  method"  is  used  in  which 
the  fixing  qualities  of  the  mordanting  fluid,  3.5  per  cent,  potassium  bichromate, 
are  aided  by  the  addition  of  osmic  acid.  Shght  modifications  are  practiced  in 
applying  the  method  for  the  different  purposes.  Bile  capillaries  usually 
require  less  time  in  both  the  bichromate  and  the  silver  nitrate  solutions  than  is 
required  for  nervous  tissues.  From  the  silver  bath,  to  obtain  more  even 
sections,  the  blocks  of  tissue  are  incisted  in  celloidin  before  cutting.  Small 
blocks  of  formalin  preserved  tissue  may  be  subjected  to  the  3.5  per  cent,  bichio- 
mate,  without  the  addition  of  osmic  acid,  and  then  treated  with  the  0.75  per 
cent,  sliver  nitrate  solution  in  the  usual  way.  When  successful,  the  prepara- 
tions from  formalin  tissue  are  most  satisfactory  in  that  the  pictures  of  the 
elements  lie  in  a  much  more  transparent  background,  and  in  that  the  precipitate 
of  reduced  silver  chromate  seems  less  liable  to  break  up  and  render  the  prepa- 
rations dift'use. 

7.  The  Benda  method  is  employed  for  the  detailed  study  of  the  neuroglia. 
The  alizarin  sulphate  in  this  method  gives  an  excellent  background  for  the 
bright  blue  neuroglia  fibres  and  nuclei  and  stains  the  endoplasm  of  the  cells  as 
well.  The  procedure  followed  by  Huber  (Am.  Jour.  Anat.,  vol.  i,  No.  i,  1901) 
is  recommended.  The  Benda  method  is  also  used  for  demonstrating  the  frame- 
work of  the  medullary  sheaths  of  axones. 

8.  Weigerfs  method  for  elastic  tissue  is  applied  to  material  fixed  in  Zenker's 
fluid.  The  fuchsin-resorcin  solutin  of  Weigert  is  applied  to  sections,  pref- 
erably paraffin  sections,  for  from  i  to  2  hours.  The  sections  are  then  washed 
in  95  per  cent,  alcohol,  dift'erentiated  in  a  0.5  per  cent,  solution  of  picric  acid 
in  95  per  cent,  alcohol,  washed  and  further  dehydrated  in  absolute  alcohol, 
cleared  in  xylol  and  mounted. 

9.  Orcein  for  elastic  tissue  fibres  is  applied  to  either  paraffin  or  celloidin 
sections,  the  latter  giving  somewhat  better  results.  The  tissue  may  have  been 
fixed  in  Zenker's  or  Van  Gehuchten's  fluid,  or  most  any  of  the  efficient  fixing 
fluids.  Sections  are  placed  in  a  watch  glass  containing  suflScient  to  well  cover 
them  of  a  I  per  cent,  solution  of  orcein  in  absolute  alcohol  to  which  there  is 
added  i  per  cent,  of  hydrochloric  acid.  The  watch  glass  is  either  put  in  a  warm 
oven  till  the  stain  evaporates  to  viscosity  (15  to  20  minutes),  or  is  covered  and 
put  aside  allowing  the  stain  to  act  for  24  hours.  The  sections  are  then  washed 
and  dehydrated  in  95  per  cent,  alcohol,  cleared  and  mounted.  If  further 
decolorization  and  dift'erentiation  is  necessary,  95  per  cent,  alcohol  containing 
0.3  per  cent,  to  0.5  per  cent,  picric  acid  may  be  used,  then  wash  in  pure  95 
per  cent,  alcohol,  clear  and  mount  as  before. 


1 82  LABORATORY    GUIDE    FOR    HISTOLOGY. 

10.  Mallory's  method  for  white  fibrous  tissue  is  used  with  paraffin  sections 
of  material  fixed  in  Zenker's  fluid.  _  After  the  parffin  is  removed  from  the  sec- 
tions, fixed  on  the  shde,  the  sections  are  carried  through  the  graded  alcohols 
to  water,  stained  5  to  10  minutes  in  o.i  per  cent,  aqueous  acid  fuchsin,  washed 
in  water,  placed  i  to  2  minutes  in  a  i  per  cent,  aqueous  solution  of  phospho- 
molybdic  acid,  then  washed  in  2  or  3  changes  of  water,  and  subjected  for  from 
I  to  10  minutes  to  an  aqueous  solution  made  by  adding  to  100  c.c.  of  boiling 
water,  i  gram  of  anilin  blue,  2  grams  of  orange  G.,  and  2  grams  of  oxalic  acid. 
From  this  staining  solution,  the  sections  are  rinsed  in  water,  dehydrated  rapidly 
with  alcohols,  cleared  in  xylol  and  mounted. 

11.  Kolossow^s  osmic-pyyo gallic-acid  metJiod  is  used  for  the  membranes  and 
for  the  structure  of  the  intercallated  disks  of  cardiac  muscle.  The  procedure 
is  that  followed  by  MacCallum  (Anat.  Anz.,  Bd.  13,  p.  609,  1897 ;  and  Kolossow, 
Zeitschr.  fiir  Wiss.  Mikros.,  Bd.  9,  p.  38,  1892).  It  is  applied  to  material  fixed 
in  alcoholic  corrosive  sublimate. 

12.  Striated  Muscle. — Pieces  of  thin  flat  muscles,  such  as  certain  of  the 
abdominal  muscles  or  the  diaphragm  of  mammals,  are  chosen  preferably 
because  their  thinness  allows  more  rapid  fixation  and  because,  in  sectioning,  the 
plane  of  section  with  reference  to  the  direction  of  the  fibres  can  be  more  easily 
controlled.  Bands  of  these  muscles,  taken  from  a  freshly  killed  animal,  are 
pinned  out  flat  and  taut  upon  cork  plates  and  placed  in  a  moist  chamber  (a  wet 
Petri-dish)  for  about  30  minutes,  to  allow  complete  relaxation  before  fixing. 
A  drop  of  strong  ammonia  water  may  be  added  to  the  moisture  of  the  chamber 
to  hasten  the  relaxation.  Then  the  cork  plates  with  the  muscle  on  them  are 
inverted  in  a  dish  containing  either  saturated  aqueous  corrosive  sublimate, 
Zenker's  fluid,  absolute  alcohol  or  Gilson's  fluid.  After  5  or  10  minutes,  the 
pieces  of  muscle,  then  stiffened  somewhat,  should  be  removed  from  the  cork  and 
placed  in  a  closed  vessel  containing  a  copious  amount  of  the  fixing  fluid,  and  set 
away  for  the  length  of  time  required  by  the  fluid- chosen.  They  are  then  washed 
as  required  by  the  fluid,  and  preserved  in  70  per  cent,  alcohol.  Blocks  of  the 
size  needed  for  embedding  are  cut  out  with  sides  parallel  and  transverse  to 
the  direction  of  the  fibres,  embedded  in  either  paraffin  or  celloidin,  and  thin 
sections  stained  lightly  in  hematoxylin.  Most  counterstains  tend  to  block  the 
detail  and  should  be  avoided.  The  structure  may  often  be  seen  quite  well  in 
unstained  sections,  especially  of  material  fixed  in  a  fluid  containing  bichromate 
of  potassium  (Zenker's,  for  example)  which  itself  leaves  a  brown  tone. 

13.  Mucins,  mucous  alveoli  and  goblet  cells  are  differentially  stained  by  the 
application  of  Mayer's  muchematin  as  employed  by  Bensley  (Am.  Jour,  Anat., 
vol.  2,  No.  I,  p.  105,  1902).  Paraffin  sections  are  required,  for,  when  applied 
to  celloidin  sections,  the  stain  gives  diffuse  pi-eparations. 

14.  Kupffer^s  method  for  sections  of  medullated  axons  is  aj)plied  as  directed 
in  Hardesty's  Neurological  Technic,  page  37.  The  application  of  0.5  per 
cent,  osmic  acid  to  the  straightened  pieces  of  small  nerve  should  be  prolonged 
to  at  least  12  hours  (the  pieces  removed  from  the  bits  of  cardboard)  and  then 


THE  GOLD  CHLORID  METHOD.  1 63 

washed  in  water  for  an  equal  length  of  time.  The  washing  from  the  fuchsin- 
absoiute-alcohol  solution  may  be  done  with  absolute  alcohol,  and  thus  the  pieces, 
already  dehydrated,  may  be  embedded  in  parafl&n  directly.  If  the  thin  sections 
do  not  show  the  axonic  reticulum  sufficiently  strong,  they  may  be  again  stained 
in  acid  fuchsin. 

15.  Tigroid  masses  (Nissl  bodies)  are  demonstrated  in  the  cell-bodies  of 
neurones  in  more  nearly  their  normal  character  by  the  application  of  er}'throsin 
and  toluidin  or  methylen  blue  than  by  the  original  Nissl  method.  Small  blocks 
of  central  nervous  system,  and  peripheral  ganglia,  are  fixed  in  96  per  cent, 
alcohol  or,  equally  well,  in  Van  Gehuchten's  fluid,  sectioned  in  paraffin  (5  to 
10  micra),  stained  on  the  slide  10  to  15  minutes  in  i  per  cent,  alcoholic  erythro- 
sin,  washed  briefly  in  50  per  cent,  alcohol,  rinsed  in  distilled  water,  and  then 
stained  in  i  per  cent,  aqueous  toluidin  blue  for  10  to  15  minutes.  The  surplus 
stain  is  then  drained  off  and  the  slide  dipped  a  time  of  two  through  i  per  cent, 
aqueous  potassium  alum,  dehydrated  and  further  difl'erentiated  by  passing 
rapidly  through  the  graded  alcohols,  cleared  in  xylol  and  mounted.  Methylen 
blue,  made  up  according  to  the  formula  of  Nissl,  may  be  used  instead  of  toluidin 
blue.  In  that  case,  the  sections  from  which  the  stain  has  been  drained  are 
differentiated  first  in  anilin-alcohol  (10  per  cent,  of  anilin  oil  in  95  per  cent, 
alcohol)  and  further  differentiated  and  cleared  with  oil  of  cajeput,  which  latter 
is  rinsed  off  in  xylol  and  the' sections  mounted. 

16.  Cajal's  method  for  netirofibrillce  is  the  most  satisfactory  in  every  way 
of  all  the  methods  employed  for  this  purpose.  Of  the  three  or  four  slightly 
dift"erent  procedures  suggested  for  this  method,  that  calling  for  fixation  in 
ammoniated  alcohol  gives  the  best  results  with  mammalian  tissue.  The  ventral 
horn  cells  of  the  spinal  cord  of  the  pig  at  term  will  be  found  especially  for- 
tunate, but  good  results  may  be  obtained  with  tissue  from  the  adult  dog  or  cat. 
Descriptions  of  the  method  by  its  author,  Cajal,  may  be  found  in  Compt.  rend. 
Soc.  Biol.,  T.  56,  No.  8,  p.  368,  1904;  also  in  Zeitschr.  fiir  Wiss.  Mikros.,  Bd. 
20,  H.  4,  p.  401,  1904;  and  in  Bibliogr.  Anat.,  T.  15,  Fasc.  i,  p.  i,  1905. 
The  embedded  tissue,  preserved  in  alcohol,  will  keep  for  months  in  the  block. 

17.  The  gold  chlorid  method  for  nerve  terminations  and  for  sympathetic 
nerve  plexuses.  Lowit's  method,  slightly  modified,  is  recommended  for  fresh 
tissue,  especially  for  nerve  endings  on  skeletal  muscle  and  tendon  and  for  the 
plexuses  of  Auerbach  and  Meissner.  A  piece  of  intestinal  wall,  or  the  bit  of 
muscle  into  which  a  nerve  twig  is  seen  to  enter,  is  cut  out  and  placed  in  10 
per  cent,  aqueous  formic  acid  for  about  5  minutes,  then  transferred,  without 
washing,  to  a  i  per  cent,  aqueous  solution  of  gold  chlorid  for  15  to  20  minutes, 
then,  again  without  washing,  it  is  placed  in  a  copious  amount  of  5  per  cent, 
aqueous  formic  acid  and  put  away  in  the  dark  for  24  hours,  or  more,  till  the  gold 
is  sufficiently  reduced.  Tissue  stained  in  this  way  is  usually  studied  by  teasing 
on  the  slide.  From  the  formic  acid  reducing  bath,  the  pieces  are  washed  in 
water  and  placed  in  glycerin  where  they  will  keep  for  years  and  from  which 
pieces  may  be  taken,  teased  on  the  sHde  and  examined  for  good  demonstrations 


184  LABORATORY    GUIDE    FOR    HISTOLOGY. 

which,  when  found,  are  isolated  and  mounted  in  glycerin  jelly.  Of  striated 
muscle,  the  plantar  muscles,  intercostals  and  abdominal  muscles  are  recom- 
mended because  of  their  lesser  thickness  and  the  ease  with  which  nerve  twigs 
may  be  traced  into  them. 

The  formic  acid  causes  the  tissue  to  take  up  water  and  swell  considerably. 
This  may  be  avoided  by  the  use  of  tissue  preserved  in  10  per  cent,  formalin 
(4  per  cent,  formaldehyde).  The  procedure  is  practically  the  same  with  this 
tissue  as  the  above  except  the  time  in  the  first  formic  acid  bath  and  in  the  gold 
chlorid  solution  is  doubled.  Applied  to  formalin  material,  the  method  is  less 
certain  than  when  applied  to  fresh  tissue,  but  when  successful,  after  formalin, 
the  results  are  more  satisfactory.  After  either  procedure,  the  tissue  may  be 
embedded  and  sectioned  in  paraffin. 

Sikler^s  hematoxylin  method  for  staining  nerve  terminations  sometimes  gives 
excellent  pictures.  However  it  requires  rather  severe  maceration  of  the  tissues 
and  takes  a  longer  time  than  gold  chlorid.  For  detailed  directions  for  any 
of  the  procedures,  the  operator  is  referred  to  the  books. 

18.  Methylen  blue  for  nerve  terminations  gives  more  delicate  results  than 
either  of  the  above  methods  and  is  resorted  to  for  terminations  of  sensory 
nerves  in  the  periphery,  especially  upon  blood-vessels,  for  terminations  in  the 
sense-organs  and  for  terminations  upon  smooth  muscle-fibres.  It  is  also  used 
for  demonstrating  the  end-brushes  of  axones  terminating  about  the  cell-bodies 
of  neurones  in  the  central  nervous  system  and  in  gangha.  When  the  animal  is 
taken  for  the  purpose  it  is  safer  to  apply  the  stain  both  intra  vitam  by  injection 
and  later,  to  bits  of  tissue  bv  immersion.  The  method,  at  best,  is  more  uncertain 
than  the  gold  chlorid  and  requires  considerable  practice.  It  is  known  as 
Ehrlich's  methylen  blue  method,  but  the  original  procedure  has  been  variously 
modified  for  different  purposes.  For  smooth  muscle,  neuromuscluar  spindles 
etc.,  the  procedure  given  by  Huber  and  De  Witt  (Jour.  Comp.  Neurol.,  vol.  7, 
p.  169,  1897)  will  be  found  trustworthy.  For  later  directions,  the  operator  is 
referred  to  the  recent  text-books  and  to  the  numerous  papers  of  A.  S.  Dogiel, 
some  of  which  papers  are  cited  in  the  literature  on  the  nervous  tissues.  When 
sections  of  the  stained  tissue  are  not  required,  Bethe's  fixing  bath  may  be 
omitted,  and  the  tissue,  taken  from  the  ammonium  picrate  solution,  may  be 
teased  in  a  mixture  of  equal  parts  saturated  aqueous  ammonium  picrate  and 
pure  glycerin  and  then  mounted  in  a  glycerin  jelly  made  up  by  using  the 
ammonium  picrate  solution  for  its  aqueous  component. 

19.  llie  Weigert  method  for  meduUated  nerve  trunks  in  the  central  nervous 
system  is  given  in  all  the  text-books.  Most  of  the  more  recent  applications 
of  the  method  involve  Pal's  modification  of  the  procedure  for  differentiation, 
namely,  the  treatment  of  the  celloidin  sections  with  potassium  permanganate, 
washing  and  subjecting  them  to  the  bleaching  action  of  sulphurous  acid, 
develojK'd  in  a  mixture  of  oxalic  acid  and  potassium  sulphite.  Dilute  sul- 
phurous acid  may  be  used^  direct.  Instead  of  tissue  fixed  in  Miiller's  fluid 
as  regularly  employed,  tissue  fixed  and  preserved  in  formalin  may  be  used. 


CARE    OF    MICROTOME    KNIFE.  1 85 

Small  blocks  of  the  latter  are  placed  in  3.5  per  cent,  potassium  bichromate  and 
kept  in  a  warm  oven  (35°  C.)  for  3  to  5  days,  the  fluid  renewed  at  the  end 
of  the  first  day.  Then  they  are  washed  in  water,  embedded  in  celloidin  and 
the  sections  treated  as  after  Miiller's  fluid.  In  either  procedure,  if,  on  trial 
the  sections  do  not  stain  deeply  enough  in  the  hematoxylin,  they  are  mor- 
danted, for  10  to  20  minutes  before  staining,  in  a  i  per  cent,  aqueous  solution 
of  chromic  acid,  after  which  they  are  washed  well  and  then  subjected  to  the 
stain.  Kulschitzky's  hematoxylin  gives  a  deeper  stain  than  that  of  Weigert's 
formula  and  is  to  be  preferred  for  most  tissue. 

THE  SHARPENING  AND  CARE  OF  THE  MICROTOME  KNIFE. 

Since  failure  to  get  preparations  most  suitable  for  study  is  frequently  due  to 
the  poor  condition  of  the  sectioning  knife,  and  since  few  students  realize  how 
delicate  a  piece  of  apparatus  the  microtome  knife  is  or  the  nature  of  the  cutting 
edge  required,  the  following  suggestions  are  offered  for  the  sharpening  and 
care  of  the  knife. 

In  the  first  place  it  is  folly  to  obtain  a  knife  of  other  than  the  very  best 
quality  of  steel,  and  one  for  general  use  in  making  celloidin  sections  should  have 
a  cutting  edge  of  not  less  than  15  centimeters.  The  author  has  found  the 
knives  manufactured  by  Wilhelm  Walb  and  by  Carl  Franck  of  very  satisfactory 
quality. 

The  nature  of  the  edge  required  is  different  from  the  ordinary  razor  edge  in 
that  it  should  be  smoothly  sharp.  The  razor  used  for  shaving  does  excellent 
work  when  its  edge  is  in  the  form  of  a  fine  saw.  A  hair  drawn  very  lightly  along 
such  an  edge  may  be  seen  to  quiver  perceptibly,  though  a  slight  increase  of 
pressure  will  sever  it  quite  readily.  The  edge  of  a  microtome  knife  should  be 
carried  beyond  the  degree  of  sharpness  of  the  ordinary  razor  edge.  It  should 
be  smoother,  and  a  hair  drawn  lightly  along  it  should  apparently  not  quiver  at 
all.  Especially  in  case  of  the  larger  sections,  required  in  the  study  of  micro- 
scopic organology,  torn  or  "ribbed"  surfaces  produced  by  a  "saw  edge"  of 
the  knife  render  the  preparations  very  unsatisfactory. 

Constant  vigilance  is  required  to  keep  a  knife  in  good  condition.  Especial 
care  should  be  taken  not  to  bring  a  needle  or  scalpel  or  any  hard  substance 
near  its  edge  while  using.  The  sections  should  always  be  handled  with  a  soft 
brush.  And  it  is  an  excellent  rule  always  to  strop  the  knife  a  minute  or  two  both 
before  and  after  using.  The  stropping  after  use  is  particularly  advisable  in  that 
it  cleans,  dries  and  polishes  the  edge,  making  it  safer  against  corrosion  when  put 
away.  Placed  in  its  special  box,  the  knife  should  always  be  kept  in  a  dry  place 
and  well  away  from  possible  fumes  of  acids.  An  apparently  slight  corrosion 
on  the  edge  means  serious  injury  to  its  cutting  quality. 

Honing. — When  the  knife  becomes  very  dull  or  when  nicks  have  been  made 
in  its  edge,  honing  is  necessary.  This  is  a  time-consuming  process,  and 
requires  more  thought  and  care  than  is  often  at  first  realized.     When  the  knife 


186 


LABORATORY    GUIDE    FOR   HISTOLOGY. 


is  ven-  badly  nicked,  or  when  poor  grinding  has  '"rounded"  its  edge,  it  is  wiser 
to  send  it  to  a  reliable  manufacturer  of  cutlery  and  have  it  ground  down  by 
machiner}'.  But  from  the  cutler,  the  edge  will  always  have  to  be  finished  in 
the  laboratory  by  light  honing  and  by  stropping  in  the  right  way.  Small  nicks 
and  ordinary  dulling  are  generally  remedied  in  the  laboratory. 

For  honing,  the  white,  Arkansas  stone,  cut  by  the  Pike  Manufacturing  Co., 
of  Pike  Station,  N.  J.,  is  much  superior  to  any  the  author  has  tried.  This 
stone  is  of  an  exceptionally  fine  grit  and,  at  the  same  time,  being  a  very  hard 
stone,  it  grinds  the  knife  rapidly.     Used  with  oil  instead  of  water,  a  hone  made 


Fig.  25. 


Fig.  26. 


of  this  stone  gives  an  edge  fine  enough  to  be  transferred  direct  to  the  strop  and 
thus  it  obviates  the  necessity  of  using  first  a  coarse  and  then  a  fine-grained  hone 
before  the  stropping.  The  hone  should  be  2-^  inches  wideband  at  least  12  inches 
long.  Obviously,  in  honing  knives  with  long  cutting  edges,  the  longer  the 
hone  the  better.  It  should  be  fitted  in  a  wooden  casing  as  shown  in  the  figures 
below,  and  the  cover  to  this  case  should  be  kept  on  when  the  hone  is  not  in  use, 
to  protect  against  dust  and  grit. 

An  excellent  procedure  in  honing  is  illustrated  in  Figs.  25  to  28.  The  hone 
is  laid  flat  on  the  table  and,  for  right-handed  operators,  should  be  arranged 
diagonally  with  the  end  toward  the  left  nearer  the  body  of  the  operator.     The 


CARE    OF    MICROTOME    KNIFE. 


187 


Stroke  in  honing  should  always  be  edge  foremost  and  the  knife  should  pass 
somewhat  diagonally  along  the  hone,  beginning  at  the  toe  of  the  blade  and 
termmatmg  at  the  heel.  Figs.  25  and  26  show  respectively  the  beginning  and 
the  termmation  of  this  stroke.  For  the  return  stroke,  involving  the  reverse 
side  of  the  blade,  the  knife  is  rotated  with  its  back  downward  and  resting  upon 
the  hone,  at  the  same  time  being  drawn  toward  the  operator  while  the  right  hand, 


Fig.  27. 


Figs.  25  to  28.— Illustrating  the  position  of  the  hone  and  the  manipulation 
of  the  knife  in  honing. 


holding  the  handle,  approaches  the  left  in  order  to  again  attain  the  diagonal 
direction  of  the  stroke.     The  position  for  the  stroke  is  then  completed  by 
letting  down  the  side  of  the  knife  flat  upon  the  surface  of  the  hone  and  the  stroke 
again  passing  from  toe  to  heel,   edge  foremost,   is  accomplished.     Figs.  27 
and  28  illustrate  in  part  the  manipulation  for  the  second  or  return  4oke 
Repetition  of  the  first  stroke  is  made  after  repeating,  at  the  right-hand  end  of 


l88  LABORATORY   GUIDE   FOR  HISTOLOGY. 

the  hone,  the  rotation  on  its  back  and  the  drawing  backward  of  the  blade; 
here,  however,  the  right  hand  is  moved  slightly  away  from  the  left  to  attain  the 
diagonal  position  assumed  when  starting  the  stroke  shown  in  Fig.  25.  Then 
follows  a  repetition  of  the  return  stroke  and  so  on,  the  two  sides  of  the  knife 
being  ground  alternately  throughout  the  process.  Especial  care  must  be  taken 
that,  during  each  stroke,  the  blade  is  kept  flat  on  the  hone,  with  the  edge  parallel 
to  its  surface,  to  insure  even  grinding.  A  slip  or  a  stroke  upon  the  corner  of 
the  hone  may  incur  a  serious  loss  of  time  to  grind  away  the  resulting  uneven- 
nesses  in  the  edge.  The  holding  of  the  blade  flat  and  parallel  upon  the  hone  is 
rendered  somewhat  easier  by  the  diagnoal  position  during  the  stroke  and  it 
may  be  further  insured  by  the  aid  of  the  fingers  of  the  left  hand,  used  as  shown 
in  the  cuts.  The  fingers  of  the  left  hand,  however,  are  used  chiefly  to  attain 
greater  pressure  upon  the  hone  and  thus  more  rapid  grinding.  Care,  of  course, 
must  be  taken  that  the  pressure  exerted  by  the  left  hand  balances  that  of  the 
right  especially  during  portions  of  the  stroke  when  the  left  hand  is  not  imme- 
diately over  the  hone.  The  aid  of  the  left  hand  should  be  renounced  toward 
the  end  of  the  required  period  of  honing. 

The  advantages  of  the  above  procedure  in  honing  lie  in  the  rapidity  and 
skill  possible  with  which  an  evenly  ground  edge  may  be  obtained.  With  a  little 
practice  of  the  strokes,  giving  special  attention  to  the  separate  movements,  a 
speed  of  two  strokes  per  second  may  be  acquired. 

Most  microtome  knives  are  made  with  one  side  plane  and  the  other  side 
concave  or  "hollow-ground"  and,  therefore,  in  honing,  the  stroke  grinding  the 
concave  side  cuts  away  the  steel  near  the  edge  more  rapidly  than  the  stroke 
grinding  the  plane  side.  Only  in  case  of  very  large  nicks  in  the  edge  should 
the  knife  be  ground  for  even  a  short  period  on  the  concave  side  only.  The 
procedure  described  above,  grinding  each  side  alternately,  is  always  safer  in 
securing  an  even  grinding  of  the  edge. 

On  request,  manufacturers  send  detachable  metal  backs  to  be  clamped  upon 
the  plane  side  of  knives  while  honing  so  that  the  edge  is  tilted  toward  the  surface 
of  the  stone,  and  may  be  ground  down  more  rapidly.  These  should  never  be 
used  except  when  great  haste  is  necessary  and  the  knife  is  very  dull,  for  the  time 
saved  then  will  have  to  be  given  later  in  bringing  the  knife  to  its  proper  con- 
dition. The  detachable  back  results,  of  course,  in  an  edge  beveled  on  both 
sides.  The  more  nearly  the  line  of  the  edge  coincides  with  the  plane  of  the 
lower  or  plane  surface  of  the  knife,  the  better,  for  in  making  sections,  the 
knife  is  used  with  the  plane  side  next  the  block  of  tissue  and  an  edge  beveled  on 
this  side  is  obviously  undesirable. 

When  the  nicks  have  disappeared  and  it  has  become  evident  that  on  the 
plane  side  of  the  knife  the  surface  of  the  stone  comes  in  actual  contact  with  the 
edge  throughout  the  stroke,  then  the  pressure  upon  the  knife  should  be  de- 
creased. It  should  then  be  honed  lightly  and  very  evenly  till  no  "wire  edge" 
is  manifest  and  till  it  will  readily  cut  a  hair  throughout  its  length.  Then  the 
knife  is  ready  for  stropping. 


STROPPING. 


189 


Stropping. — The  best  form  of  strop  for  microtome  knives  does  not  seem 
to  be  obtainable  on  the  general  market.  It  may  be  made  in  the  laboratory 
by  procuring  from  the  leather  dealer  a  piece  of  the  best  quality  of  calf-skin, 
soft,  dry  and  smooth  of  surface,  3  inches  wide  and  about  20  inches  long.  Then 
a  piece  of  inch-thick  board  of  some  solid  wood  is  cut  3  inches  wide  and  26 
inches  long,  and  one  surface  dressed  till  it  is  perfectly  plane  and  smooth.  Then, 
beginning  at  one  end,  melted  glue  is  evenly  brushed  over  20  inches  of  the  side 
especially  dressed  and  the  piece  of  calf-skin,  with  the  grain  or  epidermal  side 
outward,  is  placed  in  position  upon  the  glue,  care  being  taken  that  no  glue  gets 
upon  the  outward  surface  of  the  leather.     The  strop  should  now  be  placed 


Fig.  29. 


Fig.  30. 

Figs.  29  and  30. — Showing  the  form  of  strop  desirable  and  the  direction  of  the  two 
strokes  which  may  be  employed  in  stropping. 


between  two  strong  boards  and  the  whole  clamped  firmly  in  a  vise  and  held 
there  for  24  hours.  The  surface  of  the  clamping  board  which  presses  upon  the 
leather  should,  of  course,  be  clean  and  likewise  plane  and  perfectly  smooth. 
After  the  glue  has  "set"  well,  the  strop  may  be  removed  from  the  vise,  the 
edges  trimmed,  drops  of  excessive  glue  removed,  and  the  extra  6  inches  of  the 
length  of  the  broad  may  be  dressed  into  a  handle  for  gripping  the  strop.  The 
strop  shown  in  Figs  29.  and  30  \\as  made  in  this  way.  It,  however,  has  a 
leather  surface  26  inches  long,  a  desirable  difference  from  the  one  described 
above  but  not  essential,  and  it  is  often  difficult  to  obtain  a  strip  of  calf-skin  of 
even  quality  throughout  a  length  of  26  inches.     This  form  of  strop  is  superior 


190  LABORATORY    GUIDE    FOR    HISTOLOGY. 

to  the  common  forms  because  of  its  firm  surface.  Any  form  of  strop  with 
bending  or  even  yielding  surface  tends  to  close  upon  the  edge  of  the  knife, 
rounding  it  ofi",  instead  of  giving  the  truly  keen  edge  so  desirable  in  a.  microtome 
knife. 

The  process  of  stropping  is  quite  similar  to  that  of  honing,  except  the 
stroke  is  always  made  with  the  back  of  the  blade  passing  foremost  and 
one  end  of  the  strop  (the  handle)  is  held  in  the  left  hand  while  the  other  end 
rests  upon  the  table.  The  rotating  and  drawing  backward  on  its  back  of  the 
blade  at  the  end  of  each  stroke  are  identical  with  the  similar  movement  in 
honing.  The  stroke  shown  in  the  figures  is  diagonal  along  the  strop  and 
passing  from  toe  to  heel  of  the  blade.  In  stropping,  the  left  hand  aids  the 
right  in  giving  the  required  diagonal  direction  to  the  stroke  by  moving  the 
handle  of  the  strop  back  and  forth  as  the  downward  and  upward  strokes  are 
made.  Some  operators  make  the  stropping  stroke  passing  from  heel  to  toe, 
and  claim  that  it  is  more  efiicient  if  the  stroke  in  honing  was  made  from  toe  to 
heel.  This  claim,  however,  is  questionable  from  the  fact  that  whatever  teeth 
made  by  the  hone  with  the  knife  passing  from  toe  to  heel,  edge  foremost,  are 
probably  obliterated  more  rapidly  by  a  stropping  stroke  passing  from  toe  to 
heel  but  with  the  back  of  the  knife  foremost  and  the  stroke  diagonal  in  the 
opposite  direction  to  that  used  in  honing  the  given  side  of  the  knife. 

When  tests  with  hairs  show  that  the  knife  has  a  smooth  and  truly  keen  edge, 
it  may  be  pronounced  in  good  condition.  The  condition  of  the  edge  may  be 
judged  by  examining  it  under  the  microscope,  using  mediumly  low  magni- 
fication, if  one  has  become  sufficiently  experienced  as  to  the  appearance  of 
edges  in  different  conditions  as  seen  under  the  microscope  Place  a  fold  of 
paper  under  the  blade  to  keep  the  edge  from  touching  the  stage  of  the  micro- 
scope and  draw  the  blade  across  slowly,  keeping  the  edge  in  the  field  of 
vision.  The  smaller  and  more  even  the  teeth  shown  by  the  microscope,  the 
more  nearly  smooth  is  the  edge,  and  the  better  its  condition. 


INDEX. 


Adipose  tissue,  56 

Animal  cell,  43 

Anua,  95 

Appendix,  95 

Arteries,  76 

Atomizer  for  fixing,  7 

Auditory  apparatus,  diagram  of,  153 

literature  on,  175 
Axone,  the,  72 

literature  on,  74 

non-medullated,  73 

Bile  capillaries,  97 

Bladder,  108 

Black  pigments  for  drawing,  6 

Blenders,  7 

Blood  and  lymph,  59 

corpuscles,  determination  of  number,  62 

crystals,  60 

fibrin,  60 

formation,  64 

literature  on,  65 

pigment,  60 

platelets,  60 

vascular  apparatus,  76 
literature  on,  84 

vessels  of  encephalon,  129 
Bone,  decalcified,  55 

development  of,  56 

literature  on,  58 

macerated,  55 
Brain,  general  topography  of,  127 

introductory  exercise,  125 
Bronchi,  104 

Capillaries,  77 
Cartilage,  elastic,  54 

fibrous,  54 

hyaline,  53 

literature  on,  58 
Cardiac  glands,  93 
Cell,  animal,  43 

vegetable,  43 
literature  on,  45 

division,  44 

literature  on,  45 
Central  nervous  system,  119 

literature  on,  156 

peripheral  connections,  119 

peripheral  relations,  literature  on,  159 

reconstructions  of,  149 
Cerebello-cerebral  pathways,  diagram  of,  153 

spinal  pathways,  diagram  of,  152 
Cerebellum  and  pons,  136 
Cerebral  cortex,  structure  of,  14S 
Cerebrospinal  pathways,  diagram  of,  149 
Cerebrum,  133 

lobes  of,  134 
Circle  of  Willis,  130 
Circulatory  system,  76 

literature  on,  84 


Cochlea,  osseous  labyrinth  of,  168,  169 

membranous  labyrinth  of,  168 
Collateral  reading,  40 
Color,  drawing  in,  26 

scheines,  19 

science,  figures  illustrating,  19 
Colors  for  drawings,  8 
Colored  drawing  inks,  8 
Connective  tissue,  elastic,  52 

fibrous,  51 

literature  on,  57 

mucous,  51 

tissue  proper,  51 
Corpuscles,  white  blood,  61 
Cranial  nerves,  131 

diagram  of  pathways  of,  151 
Crayons,  8 

use  of,  26 
Cross  of  Ranvier,  72 

Digestive  apparatus,  89 
literature  on,  99 

canal,  blood-supply  of,  95 

nerve-supply  of,  95 
Differential  color,  18 
Drawing  in  colors,  26 

in  black  and  white,  9 

in  dots,  9 
'     in  lines,  10 

in  masses,  11 

methods  of,  9 

procedure  for,  28 

board,  i 

materials,  i 

papers,  3 

cutting  of,  35 

inks,  8 

pens,  5 

the  field  of  the,  13 

the  ground  color  of  the,  1 5 

the  outline  of  the,  12 

the  stage  of  detail  in,  21 
Drawings,  character  of,  39 

dift'erential  color  in,  18 

fixing  of,  7 

lettering  of,  22 

mounting  of,  24 

starting  of,  11 

in  color,  40 
Ductless  glands,  81 
Duodenum,  94 

Ear,  external,  166 

inner,  168 

middle,  167 
Economy  of  time,  38 
Encephalon,  125 

base  of,  133 

divisions  of,  human,  133 

general  divisions  of,  128 

general  topography  of,  127 

human,  129 


19] 


192 


INDEX, 


Encephalon,  literature  on,  157 

meninges  of,  126 

sections  of,  138 

superficial  blood-vessels  of,  129 

torn  preparation  of,  147 

ventricles  of,  128 
.  Embryological  development,  45 
Epithelia,  the  simple,  47 

the  stratified,  48 
Epithelium,  47 

glandular,  49 

neuro-,  50 

transitional,  49 
Equipment  for  laboratory  work,  34 
Era.?ers,  5 
Esophagus,  92 

literature  on,  99 
Examiner  board,  4 
Eye,  the,  170 

literature  on,  176 

microscopic  structure  of,  172 

tunics  of,  171 
Fabric  fibers,  43 
Fallopian  tube,  113 
Fibrin,  blood,  60 
Field,  choice  of,  38,  39 
Fixing  drawings,  materials  for,  7 

process  of,  23 
Fluid  pigment,  preparing  of,  1 7 

solution  of,  16 
Fourth  ventricle,  floor  of,  137 
Fundus  glands,  93 

Gall-bladder,  the,  97 
Genital  apparatus,  female,  in 
literature  on,  116 

male,  109 

literature  on,  115 
Glands,  cardiac,  93 

fundus,  93 

with  internal  secretion,  81 
literature  on,  86 

intercarotid,  82 

of  the  mouth,  90 

pyloric,  94 

salivary,  90 

suprarenal,  84 
Graphite  filings,  7 
Ground  color,  the,  15 

laying  of,  17 
Gustatory  apparatus,  literature  on,  175 

Hair,  the,  161 
Hand-rest,  2 

Hearing,  the  organ  of,  166 
Heart,  dissection  of,  79 

incisions  of,  78 

internal  features  of,  78 
Hemoglobin,  crystals  of,  60 

estimation  of,  64 
Hemolymph-glands,  80 
Honing  microtome  knife,  185 
Hypophesis  cerebri,  the,  82 

Inner  ear,  168 
Intercarotid  glands,  82 


Intestine,  large,  95 

small,  94 

literature  on,  100 
Introductory  exercises,  43 
Islands  of  Langerhans,  98 

Kidneys,  106 

Labelling  and  storing  slides,  33 
Laboratory  drawing,  i 

papers,  construction  of,  41 

diagrams  in,  42 

reason  for,  40 

titles  of,  42 

writing  paper  for,  42 
Laboratory  outlines,  general  instructions,  30 
Laboratory  work,  equipment  for,  34 

introductory  exercises,  43 

nature  of,  outlined,  30 
Laboratory  reagents,  use  of,  35 
Lamp  black,  7 
Larynx,  103 
Lenses,  cleaning  of,  37 

focussing  of,  37 
Lettering  drawings,  22 
Lines,  drawings  in,  10 
Lips,  the,  89 
Liver,  the,  96 

literature  on,  loi 
Lung,  the,  104 

literature  on,  105 
Lymphatic  system,  the,  80 

literature  on,  85 
Lymph-glands,  80 

vessels,  80 

Mammary  gland,  114 

Masses,  drawing  in,  11 

Material,  preparation  of,  32 

Measuring  objects  under  the  microscope,  59 

Methods  of  drawing,  9 

of  preparation,  179 
Medulla  oblongata,  137 
Meninges  of  encephalon,  126 

of  spinal  cord,  120 
Mesencephalon,  136 

sections  of,  142 
Microtome  knife,  directions  for  honing,  185 

directions  for  stropping,  189 
Microscope,  the  care  and  use  of,  36 

use  of  eye  with,  38 
Microscopic  anatomy,  76 
Middle  ear,  the,  167 
Mixing  trays,  7 
Mounting  drawings,  24 
Mouth  cavity,  the,  89 
Muscle,  cardiac,  67 

literature  on,  70 

non-striated,  67 

striated,  67 

Na'ls,  the,  162 
Nasal  cavity,  103 
Nerve-cell,  the,  71 

literature  on,  73 

terminations,  73 


INDEX. 


[93 


Nerves,  cranial,  131 
Nervous  tissues,  71 

literature  on,  73 
Neuro-epithelium,  50 
Neuro-fibrillse,  72 
Neuroglia,  the,  53 

literature  on,  58 
Neuron  theory,  literature  on,  75 
Non-medullated  axone,  73 
Nose,  larynx,  trachea,  literature,  on,  105 

Olfactory  apparatus,  diagram  of,  155 

literature  on,  175 
Olfactory  bulb,  structure  of,  166 
Olfactory  organ,  the,  165 
Optic  apparatus,  diagram  of,  155 

literature  on,  176 
Outlines  for  laboratory  work,  tinre  required 

by,  30 
Outline  of  a  drawing,  12 
Ovary,  112 
Ovogenesis,  112 

Papers,  the  laboratory,  40 

construction  of,  41 
Pancreas,  the,  98 

literature  on,  loi 
Pencils,  drawing,  5 
Pens,  5 
Pen-holders,  6 
Penis,  III 

Pharynx  and  esophagus,  92 
Pigment,  fluid,  17 
Pigments,  6 

Preparation  of  material,  32 
Prosencephalon,  134 

microscopit^  structure  of,  147 

sections  of,  144 
Prostata,  no 
Pyloric  glands,  94 

Reading,  collateral,  40 
Reagents,  use  of,  35 
Rectum,  95 
Respiratory  apparatus,  the,  103 

literature  on,  105 
Retina,  layers  of,  173 
Rhombencephalon,  136 

sections  of,  139 
Rhomboid  fossa,  137 
Ross  stipple  board,  4 

Salivary  glands,  90 
Sense  organs,  the,  160 

literature  on,  174 
Sheep's  brain,  removal  of,  125 
Simple  epithelia,  the,  47 
Skin,  the,  160 

appendages  of,  161 

blood  supply  of,  163 

literature  on,  174 

nerve  terminations  of,  163 
Slide  boxes,  34 
Slide  labels,  kind  of,  ^^ 

writing  of,  ^;} 
Slides,  size  of,  ^^ 

labelling  and  storing  of,  ^^ 

13 


Soft  palate,  90 
Spermatogenesis,  no 
Spermatosomes,  no 
Spinal  cord,  the,  119 

different  levels  of,  124 

gray  substance  of,  123 

literature  on,  156 

sections  of,  121 

white  substance  of,  123 
Spinal  nerves,  composition  of,  121 
Spleen,  the,  81 
Stage  of  detail,  the,  21 
Stipple-board,  4 
Strathmore  papers,  4 
Stomach,  the,  93 

literature  on,  100 
Storing  slides,  34 
Stropping  microtome  knife,  189 
Supporting  and  connective  tissues,  the,  51 
Suprarenal  glands,  84 

literature  on,  86 

Taste,  the  organ  of,  164 

literature  on,  175 
Teasing  needles,  35 
Teeth,  development  of,  92 

structure  o^,  91 
Testis,  no 
Thumb  tacks,  3 
Thymus,  the,  82 
Thyreoid  gland,  the,  83 
Time,  economy  of,  38 

required  in  work  outlined,  30 
Tissue,  adipose,  56 
Tissues,  methods  of  preparation,  179 

the,  47 

muscular,  67 

nervous,  71 
Titles  of  laboratory  papers,  42 
Tongue,  the,  89 
Tonsils,  the,  91 
Tortillion,  the,  7 
Trachea,  104 
Tuba  uterina,  113 
Tympanic  membrane,  167 

Ureters,  108 
Urethra,  female,  109 
Urinary  apparatus,  the,  106 

literature  on,  114 
Urino-genital  system,  the,  106 
Uterus,  113 

Vagina,  114 

Vegetable  cell,  43 

Veins,  77 

Ventricles  of  encephalon,  128 

Vermiform  appendix,  95 

Vision,  the  organ  of,  170 

Water-colors,  8 

use  of,  27 
Whatman's  water-color  paper,  3 
White-blood  corpuscles,  61 
Woods-metal  preparation,  lung,  104 
Writing  of  slide  labels,  t,^ 
^^'^iti^g  paper  for  laboratorv'  papers,  42 


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